Add 'final' to processed code based on detected usage for a given stack of layers

[jeffvroom]

We could pretty easily inject the final annotation automatically as an option so that - all methods which are not overridden are marked final by default. All properties which are not set are marked as final.

Since StrataCode compiles itself and makes poor use of final it would be a good use case to see how much of a speedup that would make.