This PR extracts the existing git change detection logic from the `get-changed-tests` script into a separate module. This allows reusing the same logic in the `run-for-change` script, ensuring consistent behavior across the two scripts to determine changed files. Specifically, this ensures that in stacked PRs, the docs-only change detection (and the test-only change detection in the upstack PR) works correctly by diffing against the appropriate base branch.
Hendrik Liebau