Make registry types not preload expensive resources

[hhyyrylainen]

The expensive resources, scenes, textures, that are inside IRegistryType shouldn't be loaded in Resolve, instead there should be some control based on the current game state, which of the resources need to be loaded, also changing what can be, to be loaded in the background would be nice. The resources would be checked to be loaded before entering the microbe stage.

Also when exiting the game state that wants specific resources loaded, the resources should be let go to let Godot handle when it wants to unload them.