- Fixes#4441: [generator] Binding with return value of Class [] do not do the right thing
(https://github.com/xamarin/xamarin-macios/issues/4441)
- Turns out the logic to put INativeObjects into NSArrays was already in place. We simply needed to add the missing (IntPtr handle, bool owns) overload to `Class`.
- Uncommented AppKit `registeredImageRepClasses` since it was using `Class []`. Tested locally and it works fine.
- Reimplemented `Foundation`'s `NSSecureUnarchiveFromDataTransformer` and its test which were also using `Class []`.