[clang] [WIP] Implement `-dump-deserialized-declaration-ranges` flag. (PR #133910)

[Ilya Biryukov via cfe-commits]

ilya-biryukov wrote:

Could you also update the PR description and change `[WIP]` to `[Clang]` in the title so that we don't accidentally forget this before comitting?

https://github.com/llvm/llvm-project/pull/133910