Implement resuming a game based on game ID

[andersfischernielsen]

Players should be able to resume a game that they've let's say left for a month by "joining" a game ID again and resuming.

This requires us to check for the ID in the database and resuming (that's why we even have a database, I guess) 😄

[andersfischernielsen]

Depending on how large the game table grows (especially with the recent versioning addition), we might need to clear out old games in intervals (e.g. every month). but resuming a two-weeks old game should be possible.

[andersfischernielsen]

Resuming games seems to be broken. This might need more work.