This relands changes in #144424 for adding a count of DWO files
parsed/loaded and the total number of DWO files.

The previous PR was reverted in #145494 due to the newly added unit
tests failing on Windows and MacOS CIs since these platforms don't
support DWO. This change add an additional
`@add_test_categories(["dwo"])` to the new tests to
[skip](https://github.com/llvm/llvm-project/blob/cd46354dbd10820158edabe14dbd49d9f9010722/lldb/packages/Python/lldbsuite/test/test_categories.py#L56)
these tests on Windows/MacOS.

Original PR: #144424

### Testing
Ran unit tests
```
$ bin/lldb-dotest -p TestStats.py llvm-project/lldb/test/API/commands/statistics/basic/
----------------------------------------------------------------------
Ran 24 tests in 211.391s

OK (skipped=3)
```

Reverts llvm/llvm-project#144424

Caused CI failures.

macOS CI failure was:
```
10:20:36  FAIL: test_dwp_dwo_file_count (TestStats.TestCase)
10:20:36      Test "statistics dump" and the loaded dwo file count.
10:20:36  ----------------------------------------------------------------------
10:20:36  Traceback (most recent call last):
10:20:36    File "/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/llvm-project/lldb/test/API/commands/statistics/basic/TestStats.py", line 639, in test_dwp_dwo_file_count
10:20:36      self.assertEqual(debug_stats["totalDwoFileCount"], 2)
10:20:36  AssertionError: 0 != 2
10:20:36  Config=arm64-/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/lldb-build/bin/clang
10:20:36  ======================================================================
10:20:36  FAIL: test_no_debug_names_eager_loads_dwo_files (TestStats.TestCase)
10:20:36      Test the eager loading behavior of DWO files when debug_names is absent by
10:20:36  ----------------------------------------------------------------------
10:20:36  Traceback (most recent call last):
10:20:36    File "/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/llvm-project/lldb/test/API/commands/statistics/basic/TestStats.py", line 566, in test_no_debug_names_eager_loads_dwo_files
10:20:36      self.assertEqual(debug_stats["totalDwoFileCount"], 2)
10:20:36  AssertionError: 0 != 2
10:20:36  Config=arm64-/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/lldb-build/bin/clang
10:20:36  ======================================================================
10:20:36  FAIL: test_split_dwarf_dwo_file_count (TestStats.TestCase)
10:20:36      Test "statistics dump" and the dwo file count.
10:20:36  ----------------------------------------------------------------------
10:20:36  Traceback (most recent call last):
10:20:36    File "/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/llvm-project/lldb/test/API/commands/statistics/basic/TestStats.py", line 588, in test_split_dwarf_dwo_file_count
10:20:36      self.assertEqual(len(debug_stats["modules"]), 1)
10:20:36  AssertionError: 42 != 1
10:20:36  Config=arm64-/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/lldb-build/bin/clang
```

## Summary
A new `totalLoadedDwoFileCount` and `totalDwoFileCount` counters to
available statisctics when calling "statistics dump".

1. `GetDwoFileCounts ` is created, and returns a pair of ints
representing the number of loaded DWO files and the total number of DWO
files, respectively. An override is implemented for `SymbolFileDWARF`
that loops through each compile unit, and adds to a counter if it's a
DWO unit, and then uses `GetDwoSymbolFile(false)` to check whether the
DWO file was already loaded/parsed.

3. In `Statistics`, use `GetSeparateDebugInfo` to sum up the total
number of loaded/parsed DWO files along with the total number of DWO
files. This is done by checking whether the DWO file was already
successfully `loaded` in the collected DWO data, anding adding to the
`totalLoadedDwoFileCount`, and adding to `totalDwoFileCount` for all CU
units.

## Expected Behavior
- When binaries are compiled with split-dwarf and separate DWO files,
`totalLoadedDwoFileCount` would be the number of loaded DWO files and
`totalDwoFileCount` would be the total count of DWO files.
- When using a DWP file instead of separate DWO files,
`totalLoadedDwoFileCount` would be the number of parsed compile units,
while `totalDwoFileCount` would be the total number of CUs in the DWP
file. This should be similar to the counts we get from loading separate
DWO files rather than only counting whether a single DWP file was
loaded.
- When not using split-dwarf, we expect both `totalDwoFileCount` and
`totalLoadedDwoFileCount` to be 0 since no separate debug info is
loaded.

## Testing
**Manual Testing**
On an internal script that has many DWO files, `statistics dump` was
called before and after a `type lookup` command. The
`totalLoadedDwoFileCount` increased as expected after the `type lookup`.
```
(lldb) statistics dump
{
  ...
  "totalLoadedDwoFileCount": 29,
}
(lldb) type lookup folly::Optional<unsigned int>::Storage
typedef std::conditional<true, folly::Optional<unsigned int>::StorageTriviallyDestructible, folly::Optional<unsigned int>::StorageNonTriviallyDestructible>::type
typedef std::conditional<true, folly::Optional<unsigned int>::StorageTriviallyDestructible, folly::Optional<unsigned int>::StorageNonTriviallyDestructible>::type
...
(lldb) statistics dump
{
  ...
  "totalLoadedDwoFileCount": 2160,
}
```
**Unit test**
Added three unit tests that build with new "third.cpp" and "baz.cpp"
files. For tests with w/ flags `-gsplit-dwarf -gpubnames`, this
generates 2 DWO files. Then, the test incrementally adds breakpoints,
and does a type lookup, and the count should increase for each of these
as new DWO files get loaded to support these.
```
$ bin/lldb-dotest -p TestStats.py ~/llvm-sand/external/llvm-project/lldb/test/API/commands/statistics/basic/
----------------------------------------------------------------------
Ran 20 tests in 211.738s

OK (skipped=3)
```

Depends on https://github.com/llvm/llvm-project/pull/142163

This patch makes the `-ast-dump-filter` Clang option available to the
`target modules dump ast` command. This allows us to selectively dump
parts of the AST by name.

The AST can quickly grow way too large to skim on the console. This will
aid in debugging AST related issues.

Example:
```
(lldb) target modules dump ast --filter func
Dumping clang ast for 48 modules.
Dumping func:
FunctionDecl 0xc4b785008 <<invalid sloc>> <invalid sloc> func 'void (int)' extern
|-ParmVarDecl 0xc4b7853d8 <<invalid sloc>> <invalid sloc> x 'int'
`-AsmLabelAttr 0xc4b785358 <<invalid sloc>> Implicit "_Z4funcIiEvT_"

Dumping func<int>:
FunctionDecl 0xc4b7850b8 <<invalid sloc>> <invalid sloc> func<int> 'void (int)' implicit_instantiation extern
|-TemplateArgument type 'int'
| `-BuiltinType 0xc4b85b110 'int'
`-ParmVarDecl 0xc4b7853d8 <<invalid sloc>> <invalid sloc> x 'int'
```

The majority of this patch is adjust the `Dump` API. The main change in
behaviour is in `TypeSystemClang::Dump`, where we now use the
`ASTPrinter` for dumping the `TranslationUnitDecl`. This is where the
`-ast-dump-filter` functionality lives in Clang.

Inferred submodule declarations are emitted in DWARF as `DW_TAG_module`s
without `DW_AT_LLVM_include_path`s. Instead the parent DIE will have the
include path. This patch adds support for such setups. Without this, the
`ClangModulesDeclVendor` would fail to `AddModule` the submodules (i.e.,
compile and load the submodules). This would cause errors such as:
```
note: error: Header search couldn't locate module 'TopLevel'
```

The test added here also tests
https://github.com/llvm/llvm-project/pull/141220. Without that patch
we'd fail with:
```
note: error: No module map file in /Users/jonas/Git/llvm-worktrees/llvm-project/lldb/test/API/lang/cpp/decl-from-submodule
```

Unfortunately the embedded clang instance doesn't allow us to use the
decls we find in the modules. But we'll try to fix that in a separate
patch.

rdar://151022173

Add an overloaded `GetTypeSystem` to specify the expected type system subclass. Changes code from  `GetTypeSystem().dyn_cast_or_null<TypeSystemClang>()` to `GetTypeSystem<TypeSystemClang>()`.

Identical PR to: https://github.com/llvm/llvm-project/pull/134563
Previous PR was approved and landed but broke the build due to bad
merge.
Manually resolve the merge conflict and try to land again.

Co-authored-by: George Hu <georgehuyubo@gmail.com>

This reverts commit 070a4ae2f9bcf6967a7147ed2972f409eaa7d3a6.

Multiple buildbot failures have been reported:
https://github.com/llvm/llvm-project/pull/134563

The build fails with:

  lldb/source/Target/Statistics.cpp:75:39: error: use of undeclared
  identifier 'num_symbols_loaded'