Fix resolving `check-dir` when changing `working-directory`

[riccardoporreca]

• Should fix #614, at least for the typical case where check-dir is a relative path.
• check-dir is now resolved relative to the working directory, as absolute path to also make it independent of the working directory of subsequent steps were the resolved check-dir-path output is used.

See run https://github.com/riccardoporreca/actions/runs/8194198667?check_suite_focus=true#step:6:169 reproducing the issue:

Warning: No files were found with the provided path: non-default-dir. No artifacts will be uploaded.

See the same case fixed when using proposed fix from the branch in run https://github.com/riccardoporreca/actions/runs/8194292727?check_suite_focus=true#step:6:155

Run actions/upload-artifact@main with: name: Linux-rrelease-results path: /home/runner/work/actions/actions/test_pkg_subdir/non-default-dir if-no-files-found: warn [...] With the provided path, there will be 54 files uploaded Starting artifact upload