If we're not touching them, we don't need to do anything special to pass
them along -- with one important caveat: due to how cmake arguments
work, the implicitly passed arguments need to be specified before
arguments that we handle.

This isn't particularly nice, but the alternative is enumerating all
arguments that can be used by llvm_add_library and the macros it calls
(it also relies on implicit passing of some arguments to
llvm_process_sources).

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.

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

Original PR: #130537
Originally reverted due to revert of dependent commit. Relanding with no
changes.

This changes the MemberPointerType representation to use a
NestedNameSpecifier instead of a Type to represent the base class.

Since the qualifiers are always parsed as nested names, there was an
impedance mismatch when converting these back and forth into types, and
this led to issues in preserving sugar.

The nested names are indeed a better match for these, as the differences
which a QualType can represent cannot be expressed syntatically, and
they represent the use case more exactly, being either dependent or
referring to a CXXRecord, unqualified.

This patch also makes the MemberPointerType able to represent sugar for
a {up/downcast}cast conversion of the base class, although for now the
underlying type is canonical, as preserving the sugar up to that point
requires further work.

As usual, includes a few drive-by fixes in order to make use of the
improvements.

Reverts llvm/llvm-project#132234

Needs to be reverted due to dependency.

This blocks reverting another PR, see here:
https://github.com/llvm/llvm-project/pull/131965#issuecomment-2741619498

Original PR: #130537
Reland after updating lldb too.

This changes the MemberPointerType representation to use a
NestedNameSpecifier instead of a Type to represent the base class.

Since the qualifiers are always parsed as nested names, there was an
impedance mismatch when converting these back and forth into types, and
this led to issues in preserving sugar.

The nested names are indeed a better match for these, as the differences
which a QualType can represent cannot be expressed syntatically, and
they represent the use case more exactly, being either dependent or
referring to a CXXRecord, unqualified.

This patch also makes the MemberPointerType able to represent sugar for
a {up/downcast}cast conversion of the base class, although for now the
underlying type is canonical, as preserving the sugar up to that point
requires further work.

As usual, includes a few drive-by fixes in order to make use of the
improvements.

This patch pushes the error handling boundary for the GetBitSize()
methods from Runtime into the Type and CompilerType APIs. This makes it
easier to diagnose problems thanks to more meaningful error messages
being available. GetBitSize() is often the first thing LLDB asks about a
type, so this method is particularly important for a better user
experience.

rdar://145667239

LineSeqeunce is basically a vector, except that users aren't supposed to
know that. This implements the same concept in a slightly simpler
fashion.