Non-host players can select game

[ComradeVanti]

Describe the bug
Currently there is nothing stopping anyone in the room to send a "selectGame" event and change the selected game. This would of course require a little bit of hacking on the client-side but its not impossible.

To Reproduce
Modify the frontend app on the client-side in a way, that it thinks it is host. It will then allow the player to select a different game, which the server allows.

Expected behavior
No players except the host should be able to select the game. Check if the requesting player is host and if not block the request.