Add make commit-lint target to help contributor validate commit message locally before submitting

[sthaha]

Often PRs are blocked because the commit-lint action fails - e.g. #304 fails
because of commit-lint https://github.com/rhobs/observability-operator/actions/runs/5377063687/jobs/9760871220

It would reduce rework and toil if we provided a make target - commit-lint which allows contributors to validate commit messages locally.

It does help if all they have to run is make lint to ensure all lints are caught before submission.