[clang-tools-extra] [run-clang-tidy, clang-tidy-diff] Accept directory as value for -export-fixes (PR #69453)

[Amadeus Gebauer via cfe-commits]

amgebauer wrote:

>From my side it is ready to be merged. I don't have the access rights to do so.

https://github.com/llvm/llvm-project/pull/69453