Add automation to the repository for testing/linting/etc

[AngeloStavrow]

If you care about something, you should automate it.

— Komondor README

It's best to spend time solving problems, not the administrivia of tabs-versus-spaces. To that end, automation for things like linting, formatting, and testing would be helpful.

We could use GitHub Actions in some cases, but again, that ties us to GitHub. IMO, it's better instead to leverage Git Hooks via Komondor for our package.

A fairly useful initial setup would be to set up a pre-commit hook that:

• Runs SwiftLint and SwiftFormat
• Builds the package
• Runs the unit tests
• Runs SwiftDoc
• Cleans up the generated docs (per this comment on Add documentation on public methods/functions #2)

[AngeloStavrow]

This is (mostly) done in 7fd1c6a, so I'm closing this issue.