Lobby system

[andreiBe]

WIP. I removed the path option from the CLI. It can be added back if needed. There is right now no indication of the child process lobby server running.

[andreiBe]

This pull request adds the early version of the lobby system. The system does not currently include any countdowns. Instead the flow is:
--> Waiting for players until minimum players is reached
--> Voting for a map until everyone has voted
--> Selecting champions until everyone has selected
--> Game begins

The lobby does not yet actually launch the paladins server. It just marks the state as "game in progress".

Testing
Open the server list and press host server. Select "public server" and increase the minimum players to, for example, 4. The lobby server will open in the background and appear in the server list after some time. Clicking the server on the server list makes you join the lobby. I created a debug URL that I usually open in the browser: http://localhost:1420/debug-lobby The debug URL makes it possible to add new players and make their map and champion selections.

TODO
Better error handling
Indication of lobby server running in the background
Separate UI into components
Improve the look and responsiveness of UI
Kick players after long disconnect

[andreiBe]