Rewrite frontend to only use API endpoints

[hwittenborn]

Description of feature.

This is a long-term goal, but something I think would be very beneficial towards the maintainability of the MPR platform.

The current idea is that the backend API would still be written in Python, but the frontend could be entirely written in Javascript using React or something similar, preventing us from having to maintain both Jinja templates and separate Javascript. I also want to look into using Deno, and this would provide an excellent opportunity to do such.

[hwittenborn]

I guess Fresh might be the defacto standard eventually, and it supports a React-like system, so we'll probably use that.