Add husky & commitlint to enforce conventional-commit messages

[timoxley]

This adds a commit message git hook that should "enforce" the type(scope): format for commit messages.

There are other rules but I've relaxed them a bunch and also set it not run during rebases.

If you find any of these rules annoying, please let me know and we can just disable it.

If there's a problem with the validation and you really need to skip this hook, you can always run your git commands with the --no-verify flag, e.g.

git commit --no-verify 

Currently this is not validated in CI, local only.

Open to expanding the list of types or maybe enforcing list of scopes.
Possible this may cause issues with the gh-pages action, since it's writing commits to the gh-pages branch. update: Fixed by adding additional types.

[fonty1]

Any thoughts on how this should be communicated with 3rd party devs that want to commit a fix. Perhaps a 'Contributing' section in the readme docs? I can do that in a separate PR if you'd like

[jtakalai]

Interesting stuff

[timoxley]

Perhaps a 'Contributing' section in the readme docs?

@fonty1 Great idea. Once this PR lands, the tooling will enforce the commit message shape, but a section about formatting messages for contributors would be good in addition to this.

@fonty1 can you draft up a CONTRIBUTING.md file for the project root, linked to by the README.md? Using a CONTRIBUTING file means it would start appearing as a link in Issues/PRs i.e. https://docs.github.com/en/github/building-a-strong-community/setting-guidelines-for-repository-contributors