Add a ci job for homebrew-tools-public to run `ci/lint.sh` and `ci/test.sh` on each MR and on each commit to main

• add a new workflow to https://repo1.dso.mil/big-bang/pipeline-templates/pipeline-templates under pipelines/homebrew-tools-public.yaml
  • in a lint job, run ci/lint.sh
  • in a test job, run ci/test.sh
    • the test job will probably need to be tweaked to use kaniko or buildah rather than the current docker-in-docker option
  • these ci scripts should be landing in this repo as soon as !3 (merged) is merged
• register it as the gitlab CI yaml for this repo (will need an admin to do this, maybe @jfoster)