In scenarios where we have a type that isn't a WinRT type, but implements WinRT interfaces, we previously went through the interfaces and determined the most derived one to return as the runtime class name. This is not trim friendly. With these changes, we will do this in the AOT source generator rather than at runtime and instead at runtime lookup the attribute on the type. This also allows the opportunity for someone in this scenario to specify their own class name if desired as today if there are multiple interfaces that don't inherit from each other, we will need to choose one and that might not be what is desired by the author.

In addition to the scenarios where we put the attribute on the type, there are a couple scenarios where the type isn't authored in the component but rather a system type. To handle these scenarios, we use the lookup table similar to what we do in the CCW vtable scenario.