[clang] [Clang] [NFC] Introduce `ConstDynamicRecursiveASTVisitor` (PR #122991)

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https://github.com/cor3ntin approved this pull request.

I wonder if we want to apply the MaybeConst traitment to RAV in the future.

For now, this looks good

https://github.com/llvm/llvm-project/pull/122991