Use Vite instead of CRA

[aflatter]

I was curious about replacing CRA (which is not being worked on anymore) with Vite (which is probably the most direct replacement).

Notes:

• eslint is configured tol run as part of the development server (as in CRA). Issues are displayed using the checker plugin.
• All JS files that contain JSX have been renamed to .jsx as that's the easiest way to make them work with Vite.
• I decided to go with SWC instead of Babel. Who doesn't like more efficient builds?
• There don't seem to be any tests currently, so I have not integrated a testing setup.

Todos:

• Make sure the CI passes
• Make sure the run_rebuild.sh still behaves as intended.

[aflatter]

@pabera I set up the Docker environment as per the docs and fixed the port allocation. Marked the PR as ready for review to trigger the CI. Let me know if there's anything else I should check.