Part of [ENG-5153](https://linear.app/comm/issue/ENG-5153)
Depends on D9397
We would like to separate hosting web app on dev environment to `localhost:3000/webapp/`` and move the keyserver logic to `localhost:3000/keyserver/` (so in the end nothing will be hosted on `localhost:3000/`) to simplify the dev environment and allow for web <-> keyserver separation. We can also use this opportunity to cleanup the naming. This diff automatically adds new files on nix start. They will be used in the later diff.