This commit adds a '/metrics' endpoint in the API that can be exploited by Prometheus.
This endpoint returns:
- the number of connected sockets
- the number of users per room
- common NodeJS and system metrics
WARNING: this endpoint is public right now and should be protected
- Add all map json in back
- Create middleware to check authentification user
- Create controllers to get map
- Create access to get all files in folder Assets/Maps
