Fix broken dev environment set-up

Related issue: #1726 (closed)

This Merge Request includes:

• A changelog fragment (cf https://docs.funkwhale.audio/contributing.html#changelog-management)

Restores development with docker. I'm not sure if server option in vite.config.js would break production env, or it only affects dev environment. Maybe @wvffle could check it?

I also had to change Content-Security-Policy in nginx's conf.dev. Other than that I'm pretty confident with the other changes.