[Backend] Make certificate available for production server

Summary

At the moment we cant run the server in production mode (https) as we do not have the certificates available.

Possible fixes

Once the cert and key files are available we have to load them on server launch: In the app/server.ts we have to add. Additionally also have to think about a way to start the http server in dev mode (i.e. if config.NODE_ENV !== "production") !

import { createServer } from "https";
/*
...
*/
const httpsOptions = {
  key: fs.readFileSync("./certificate.key"),
  cert: fs.readFileSync("./certificate.crt"),
};
/*
...
*/
const https_server = createServer(httpsOptions, async (req, res) => {
    /*
    ...
    */
}