Single stage init for MapViewState game loading

[DanRStevens]

Currently MapViewState has a constructor overload taking a saved game name, which it stores locally, and then completes the load later during initialize. We should instead use single stage initialization, where the full load is done by the time the constructor completes, and if there was any error loading, it should throw from the constructor, preventing object instantiation. This prevents creating zombie objects which exist, and can have methods called, but don't really work because they're in some kind of failed state.

Related:

• Issue Transition StructureManager away from being a global #1647
• Issue Convert StructureCatalogue from static class to regular class #1336
• Issue Convert ProductCatalogue from static class to regular class #1337