Clean up typeystem query type method

[jcklie]

Is your feature request related to a problem? Please describe.
Right now, we have methods for checking type info like is_instance in three places, standalone functions, on Type and on Typesystem. It would be nice to unify them somehow if that makes sense.

[reckart]

Any specific idea how to unify them?

[jcklie]

Maybe only put them on the type or remove them atleast from the type system. If one adds a new function like these, it needs to be added in 3 places right now to adhere to the existing ones.