[clang] [clang][ASTMatchers] format ASTMatchers.h (PR #203766)

[Baranov Victor via cfe-commits]

vbvictor wrote:

> Is there a reason why the formatting is needed? Part of our developer policy is to not make these kinds of changes unless there's a reason because of the amount of problems it causes for downstreams due to merge conflicts. So it's not that we can't do it, it's that we want there to be a good reason. (If there is a reason for the change, I'd recommend updating the summary to explain them.)

Yeah.. thank you for the pushback, I thought it was not a big change to the file.
The motivation was that I kept forgetting to run git-clang-format instead of regular format thus formatting whole file..
I don't have any more specific reasons, will close the PR soon if nothing new show up.

https://github.com/llvm/llvm-project/pull/203766