[Feature] - Rename IContest.GetFunctionType #389

It's rather confusing to write a test or demo app (or any app really) that doesn't use debugging information. All the other overloads use "Create" as the verb. The verb "get" presumes the thing already exists.

Describe the solution you'd like

public IFunctionType CreateFunctionType( ITypeRef returnType, IEnumerable<ITypeRef> args )`

Describe alternatives you've considered
[None] a simple name change makes it clear what the function does.

Additional context
This is a breaking change unless the old name is retained and marked as "obsolete" but remains. Removing the "Get" named function is a breaking change.