Add Copy trait for builtin

[illusory0x0]

• Add Clone trait for builtin #1425

if a container type always mutable and element type is Immutable, we just invoke copy method to impl Clone trait.

if we hava Functor trait and Copy trait, we can simply get a default implementation

impl[T : Clone] Clone for Array[T] with mutability() { Mutable }

impl[T : Clone] Clone for Array[T] with clone(self) {
  match T::mutability() {
    Mutable => self.map(T::clone)
    Immutable => self.copy_array()
  }
}

[Lampese]

I also think that if we had Clone traits, then Copy traits would be necessary, similar to Rust, but is Functor traits really necessary?

cc @peter-jerry-ye

[peter-jerry-ye]

I think the proposal is simply unnecessary.