Add linting and test checks

[krowvin]

I have noticed some of our other code fails to pass a linter. In the hopes of ensuring I don't accidentally leave unused imports, fail on var scope, and other things I wanted to enable a linter at least at the library level for future PRs.

Summary

• Add pull request checks that run linting and Vitest. Hopefully prevent future lint errors.
• Fix existing lint violations so the lint check can pass with --max-warnings 0.
• Preserve existing component defaults while addressing props that were previously unused.

Closes #269

Verification

• npm.cmd run lint
• npm.cmd test -- --run (In the CI now)
• npm.cmd run build-lib -- --emptyOutDir=false

[github-actions]

Please set a versioning label of either major-bump, minor-bump, or patch-bump to the pull request.