Newtype macros for wrapping non-reflect types (`Component`, `Resource`, `Asset` etc.)

The ecosystem has many examples of types which do not implement reflect, and while submitting PR's in each repo is one way to deal with that problem, it's not the nicest.

It would be good to empower users of BMS to wrap types in external crates, to create wrapper component/resource types which sync to the underlying types, to allow manipulation from scripts