Add Prettify and Lint scripts for each sub-project and top level client

[Durbatuluk1701]

Main Highlights:

1. Yarn scripts for running the prettifier (in-place prettifies files) and linter
2. Linter made stricter
3. Typechecker made stricter (no explicit typecasting with as, tries to force exhaustive switch statements, etc.)
    

I think this should hopefully allow for some development quality of life improvements.

One thing I will mention, it feels duplicative (albeit the most expressive) at the moment to have each sub-project carrying its own prettier, linter, and TS config.
Should I explore trying to collapse these into one top level config that applies to the sub-projects as well, or let each sub-project configure itself in case it needs more fine-grained control?

Another question: Should enforcing meeting the style standard (prettier --check .) be a test/requirement checked in CI build?

[Durbatuluk1701]

If the new rules and changes seem good, I think I will run yarn run prettify:all and yarn run lint:all, fix any lint issues, then hopefully the whole client dir will be consistent