Typescript migration

[lit26]

Add typescript migration for the frontend

[pastelsky]

Thanks for the pull request @lit26 — really appreciate the time you took to create this. But it looks like this PR also refactors class components to functional components, and makes other logic changes at a few places.

Due to this —

1. We would lose git history for existing files since these aren't detected as renames
2. It is difficult to review since the diffs are not very meaningful and there are quite a changes occuring at the same time.

I'd request sharding the changes, and do them one at a time —

1. Just the TS migration.
2. Class -> function components
3. Any other logic changes / fixes

[lit26]

Will do. Can I switch step 1 and 2? A little bit easier for me.

[lit26]

Split steps in other PR.