[Dev] want to improve storage mod about IntoSuper code

[nkysg]

May be we can get a better code. Is it possible to refactor these code?
** Related Code **

starcoin/storage/src/lib.rs

Lines 612 to 625 in 6c0546e

	impl<'a, T: 'a + StateNodeStore> IntoSuper<dyn StateNodeStore + 'a> for T {
	fn as_super(&self) -> &(dyn StateNodeStore + 'a) {
	self
	}
	fn as_super_mut(&mut self) -> &mut (dyn StateNodeStore + 'a) {
	self
	}
	fn into_super(self: Box<Self>) -> Box<dyn StateNodeStore + 'a> {
	self
	}
	fn into_super_arc(self: Arc<Self>) -> Arc<dyn StateNodeStore + 'a> {
	self
	}
	}

[nkysg]

rust-lang/rust#65991, may be we could use trait_upcasting in the future.