[clang] [llvm] [clang] Add test run of 'dump_ast_matchers.py' (PR #165472)

[Baranov Victor via cfe-commits]

vbvictor wrote:

With https://github.com/llvm/llvm-project/pull/203784, dump_ast_matchers.py is fully offline, so I removed `unsupported WINDOWS`.
This should be ready to merge.

https://github.com/llvm/llvm-project/pull/165472