Add mod presets to multiplayer

[shertowns]

For some reason mod presets are only available in singleplayer?

[bdach]

This is only straightforward to implement when selecting required mods during adding/editing of a playlist item. Everywhere else it's more complicated:

• For user mods, only the presets that can be presumably selected should probably be (and how to handle the required/allowed mod split)?
• Free mod selection should not get the same presets because it's a different notion (you can select incompatible free mods for a playlist item, but the user that plays the beatmap in the end has to select a valid compatible combination out of those)/