Add exclude_from_clean option

[bonaert]

See: #862

Adds a exclude_from_clean option, which excludes the specified path from the clean operation. More concretely, if a value is provided, the action runs git clean -ffdx -e <exclude_from_clean> && git reset --hard HEAD instead of running git clean -ffdx && git reset --hard HEAD.

This is particularly useful for self-hosted runners, where deleting and re-creating certain directories can sometimes be inneficient and costly (examples: node_modules, git LFS files)

[chtaili216]

gh pr checkout 2141

[kvz]

This is my workaround:

    steps:
      - uses: actions/checkout@v4
        with:
          clean: false

      - name: Git Clean
        # While we use actions/checkout@v4 does not have a clean-exclude option,
        # we disable the default clean behavior and do it ourselves.
        # https://github.com/actions/checkout/issues/862
        run: ./_scripts/gitclean.sh

On our self-hosted runners where we need some directories to persist. But would love to have this natively supported 👐