Support PCP type healing for higher kinded types

[nicolasstucki]

Currently

def f[T, S[_]](implicit ev: Type[S[T]]): Any = '{
  val a: S[T] = ???
}

fails with

15 |      val a: S[T] = ???
   |             ^
   |            access to type S from wrong staging level:
   |             - the definition is at level 0,
   |             - but the access is at level 1.
   |            
   |             The access would be accepted with the right type tag, but
   |             no implicit argument of type scala.quoted.Type[S] was found
15 |      val a: S[T] = ???
   |               ^
   |            access to type T from wrong staging level:
   |             - the definition is at level 0,
   |             - but the access is at level 1.
   |            
   |             The access would be accepted with the right type tag, but
   |             no implicit argument of type scala.quoted.Type[T] was found

When healing the types we just do not try to find implicit Type for applied higher kinded types. To support this it looks like we need to handle AppliedTypes in PCPCheckAndHeal.checkType before trying to heal it's parts.

[nicolasstucki]

Later, we could add better support for HK type by providing context bounds for them and combining them with Types automatically.

  def f2[T: Type, S[_]: HK1Type]: Any = {
    '{
      val a: S[T] = ???
    }
  }

  class HK1Type[Y[_]] {
    def apply[X](x: Type[X]): Type[Y[X]] = ??? // implemented by the compiler
  }

  implicit def ev[X, Y[_]](implicit x: Type[Y], y: HK1Type[S]): Type[Y[X]] = y(x)