feat: provide option to run only on provided list of files (such as changed-files output)

[eripa]

Checklist

• This Feature Request only contains 1 request (if you have multiple open multiple feature requests).

The idea

I want to enable the shellcheck action on a repository that has many many scripts of varying quality. So I am trying to build a workflow that is using the changed-files action to gather only files that this change touches, and run shellcheck on those.

      - name: Get changed shell scripts
        id: changed-files
        uses: tj-actions/changed-files@v46
        with:
          files: |
            **/*.sh

Would it be possible to allow this action to take the input of the changed-files action and use that as the source for shellcheck?

Implementation

Something like:

- name: Run shellcheck on changed files
  uses: ludeeus/action-shellcheck@master
  with:
   only_files: ${{ steps.changed-files.outputs.all_changed_files }}

I could see that you might want to still respect the ignore options.

Alternatives

This is what I currently do as a workaround:

      - name: Copy changed scripts into a clean directory
        run: |
          set -euo pipefail
          mkdir -p changed-scripts
          echo "${{ steps.changed-files.outputs.all_changed_files }}" \
            | tr ' ' '\n' \
            | while read -r file; do
                [ -f "$file" ] || continue
                cp --parents "$file" changed-scripts/
              done

      - name: Run ShellCheck on only those scripts
        uses: ludeeus/action-shellcheck@master
        with:
          scandir: changed-scripts

The problem here is that the output/file dir doesn't match the actual source, so it shows changed-scripts/.. instead of the actual location.

It also makes the action setup a bit clunky.

ShellCheck - shell script analysis tool
version: 0.10.0
license: GNU General Public License, version 3
website: https://www.shellcheck.net
Run declare -a options
Run declare -a excludes
Run declare -a files
Run statuscode=0
changed-scripts/util/my-script.sh:3:8: note: Not following: ./deprecated.sh was not specified as input (see shellcheck -x). [SC1091]
changed-scripts/util/my-script.sh:21:41: note: Double quote to prevent globbing and word splitting. [SC2086]
changed-scripts/util/my-script.sh:24:13: warning: Quote this to prevent word splitting. [SC2046]
changed-scripts/util/my-script.sh:27:20: note: Double quote to prevent globbing and word splitting. [SC2086]
changed-scripts/util/my-script.sh:30:16: note: Double quote to prevent globbing and word splitting. [SC2086]
changed-scripts/util/my-script.sh:31:14: warning: Quote this to prevent word splitting. [SC2046]
Run exit 1
Error: Process completed with exit code 1.

Additional context