[clang] [llvm] [GitHub][CI] Add running of 'dump_ast_matchers.py' to premerge workflow (PR #165472)

[Baranov Victor via cfe-commits]

vbvictor wrote:

> Why do we need to do something in the code formatting action that's completely custom instead of something like https://github.com/llvm/llvm-project/pull/118154?

Thank you for reference, I implemented it the easy way. ~Though formatting message looked cool~

The job will fail till we land, https://github.com/llvm/llvm-project/pull/165448.

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