Add formatting checks to pre-commit hook and CI

[justanotherariel]

Proposed Changes

• Add husky + lint-staged to run Prettier and ESLint on staged .ts files before commit
• Add prettier --check step to CI lint job
• Include tests/ in the format script
• Format all files which weren't formatted before

[edenhaus]

Will husky be executed similar to prek before committing?

[justanotherariel]

Yes. It's the pre-commit hook usually used in node applications. On commit, prettier and the linter (defined in package.json:27) will check all files and fix if possible automatically. Only staged files are looked at.

[edenhaus]

But I don't see any changes to it will be setup correctly. Will it be done automatically?
otherwise we need to extend at least the devcontainer

[justanotherariel]

Yes, should be automatic. Devcontainer already runs 'yarn install' which will set up husky.