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).

This patch replaces the use of `UINT32_MAX` as the error return value of
`GetIndexOfChildWithName` with `llvm::Expected`.


# Tasks to do in another PR

1. Replace `CalculateNumChildrenIgnoringErrors` with
`CalculateNumChildren`. See [this
comment](https://github.com/llvm/llvm-project/pull/136693#discussion_r2056319358).
2. Update `lldb_private::formatters::ExtractIndexFromString` to use
`llvm::Expected`. See [this
comment](https://github.com/llvm/llvm-project/pull/136693#discussion_r2054217536).
3. Create a new class which carries both user and internal errors. See
[this
comment](https://github.com/llvm/llvm-project/pull/136693#discussion_r2056439608).

TestStructuredDataAPI.py fails with Python debug build ver. 3.12+ due to
call to Py_XINCREF while GIL is not held.

So the dSYM can be told what target it has been loaded into.

When lldb is loading modules, while creating a target, it will run
"command script import" on any Python modules in Resources/Python in the
dSYM. However, this happens WHILE the target is being created, so it is
not yet in the target list. That means that these scripts can't act on
the target that they a part of when they get loaded.

This patch adds a new python API that lldb will call:

__lldb_module_added_to_target

if it is defined in the module, passing in the Target the module was
being added to, so that code in these dSYM's don't have to guess.

Since the inner wrapper call might have removed one of the entries from
the global dict that the outer wrapper ALSO was going to delete, make
sure that we check that the key is still in the global dict before
trying to act on it.

Should fix the following compile error on Windows:

  C:\Python312\include\pyconfig.h(225): error C2371: 'pid_t': redefinition; different basic types
  C:\buildbot\as-builder-10\lldb-x-aarch64\llvm-project\lldb\include\lldb/Host/windows/PosixApi.h(80): note: see declaration of 'pid_t'

This patch improves the synchronization of the debugger's output and error
streams using two new abstractions: `LockableStreamFile` and
`LockedStreamFile`.

 - `LockableStreamFile` is a wrapper around a `StreamFile` and a mutex. Client
   cannot use the `StreamFile` without calling `Lock`, which returns a
   `LockedStreamFile`.

 - `LockedStreamFile` is an RAII object that locks the stream for the duration
   of its existence.  As long as you hold on to the returned object you are
   permitted to write to the stream. The destruction of the object
   automatically flush the output stream.

Remove Debugger::GetOutputStream and Debugger::GetErrorStream in
preparation for replacing both with a new variant that needs to be
locked and hence can't be handed out like we do right now.

The patch replaces most uses with GetAsyncOutputStream and
GetAsyncErrorStream respectively. There methods return new StreamSP
objects that automatically get flushed on destruction.

See #126630 for more details.