Support derivation for types with implicit parameters in the type signature

[buzden]

Implicit arguments were always supported at the derivation task and in constructors of derived types, but as a curious case, were never supported in the types themselves, which is unfortunate.

[buzden]

As an example of such type, one can consider

data X : Vect n a -> Fin n -> a -> Type where
  Here : X (x::xs) FZ x
  There : X xs n y -> X (x::xs) (FS n) y

Here we have n and a to be an implicit type arguments in the type signature of X