[#2495] Allow prepareData methods to be called on module actors

[arbron]

• SystemDataModel now inherits from TypeDataModel
• Renamed _prepareBaseData on GroupData to match naming in core
• Adjusted data preparation to ensure TypeDataModel preparation methods are still called

[Fyorl]

I have a suspicion that TypeDataModel is v11-only, which is why we do not use it currently. That's also why I opted to check game.template for the types rather than checking system.modelProvider.

The rest of the changes look fine to me except that we might have to continue manually calling GroupActor#prepareBaseData for now while we have v10 compatibility.

It's unclear whether #2495 can be resolved without inheriting from TypeDataModel. I don't know if we want to punt this issue to a later version where we drop v10 support, or whether we can dynamically inherit from DataModel or TypeDataModel based on game.release.generation.