Implement Typed for UserDataRef(Mut)

[selaux]

Not sure if that was intentionally omitted, but Typed should probably also be implemented for UserDataRef and UserDataRefMut. You can pass references to user data to a function by using those. This adds the two implementations.

[Tired-Fox]

@selaux

Can you also add tests into type_file_tests.rs and luau_type_file_tests.rs to prove that the output is as expected. Can be something like a function type that takes these types as parameters and the output would be ---@param param0 string or something similar with the function signature.

[selaux]

I think I got everything now. The tests are a bit more extensive than requested, because to test the UserDataRef<T> I had to construct a type T that already implements UserData and Typed, so I decided to also implement TypedUserData for the functions. In the end I ended up testing all of the functionality of TypedUserData where the functions / methods take UserDataRef and UserDataRefMut.

[Tired-Fox]

I think I would rather have it be detailed enough to make sure everything works as expected. I will review it again and try to get it in sometime today.