[llvm] [clang-tools-extra] [clang] [clang-tidy] modernize-use-digit-separator issue #35414 (PR #76153)

[Piotr Zegar via llvm-commits]

https://github.com/PiotrZSL requested changes to this pull request.

Did some quick glace, some work still needed, my main concern is performance of this check.

https://github.com/llvm/llvm-project/pull/76153