The workflow plugin blocks staging of empty commits to act as a safeguard against double-merging of changes which would create a second, empty patchset.

Implementation of this new rule overlooked the use case where a [ChangeLog] tag in a commit message is used to update changelog generation, without touching any code in the same commit. This technically counts as an empty commit since no files are touched.

We can keep the new blocking behavior if we also implement an exception system.

Proposed fix: Use the internal gerrit user's git config at ~/.gitconfig to read from a new section `qtcodereview`, and a new key in that subsection `emptyCommitExceptions` to define a comma-separated list of whitelisted commit-message search values which cause the plugin to bypass the empty-commit check.