Add server-side models for ranked play

[smoogipoo]

	Old Server	New Server
Old Client	🟢	🟢
New Client	🔴	🟢

The most important change here that contributes to the above crosstable, is that I've renamed GetMatchmakingPools() to GetMatchmakingPoolsOfType(). This is for two reasons:

1. To add the pool type parameter.
2. Because SignalR does not support method overloads.

The idea here is the server can add a GetMatchmakingPools() (old name) method, redirect it to the QuickPlay type, and old clients will continue behaving correctly.

[smoogipoo]

In general, I'm using "matchmaking" to refer to quick play. I'm hoping to do a whole codebase refactor at some point to fix namespace/class namings, but this particular member is a different beast because it is a databased value.

[bdach]

loose thoughts about possible representation issues, no follow-up expected on any of these

[bdach]

@peppy not sure if you want to go over this

[peppy]

@bdach happy to leave in your hands 👍