Feature request: Allow to configure the git clean parameters

[0x53A]

We are using self-hosted runners and would like to persist certain cache directories between runs.
It would be really useful if the clean parameter could be extended from a bool to a string.

For example, in gitlab I can set

variables:
    GIT_CLEAN_FLAGS: "-ffdx -e DirectoryIWouldLikeToKeep"

This should even be backwards compatible by first checking if clean is either true or false.

[EluvK]

Encountered the same problem, the compromise I used was to run git clean manually.

- name: Checkout repository
  uses: actions/checkout@v3
  with:
    clean: false

- name: Run Git Clean
  run: git clean -ffdx -e cache_directory/

Still need this feature to make it more elegant.