[Items] GetValueOrDefault + No Base Stats

- Added some extension methods for getting default values from item collections.
- Removed the hardcoded base stats from item creation.
[Stats] No Genericized Stat Collections

- I think so far for my other collections I cleaned up the collections with type parameters that allowed storing collections of mutable vs immutable interfaces.
- Stats was still left over, and it looked like nobody was really requiring stat collections with mutable stats.
[Actors] GetValueOrDefault + Tests

- Removed stat initialization and leverage the extension method GetValueOrDefault instead.
- Added some simple initialization tests.
[Items] Save State

- Experimenting with a class that is used to transform application layer items into data layer items.
- The save method isn't complete, but as I fill out unit tests, I can start to make that portion work.