Extension System: stable extension_id calculation

[indirection42]

Currently, the extension_id is simply calculated on AST level which is not only stable. see:

XCQ/xcq-extension/procedural/src/lib.rs

Line 171 in 3c0d9b4

fn calculate_hash(trait_items: &[TraitItem]) -> u64 {

Theoretically, we want two trait methods sets produce the same extension id, after the resolution of type aliases.
However, the type aliases can be defined out of the TokenStream that current proc-macro-attribute processed. So how we do with it?

XCQ/xcq-extension-fungibles/src/lib.rs

Lines 4 to 19 in 3c0d9b4

	pub type AccountIdFor<T> = <<T as ExtensionFungibles>::Config as Config>::AccountId;
	pub type BalanceFor<T> = <<T as ExtensionFungibles>::Config as Config>::Balance;
	pub type AssetIdFor<T> = <<T as ExtensionFungibles>::Config as Config>::AssetId;
	#[extension]
	pub trait ExtensionFungibles {
	type Config: Config;
	// fungibles::Inspect (not extensive)
	// fn total_inssuance(asset: AssetIdFor<Self>) -> BalanceFor<Self>;
	// fn minimum_balance(asset: AssetIdFor<Self>) -> BalanceFor<Self>;
	fn total_supply(asset: AssetIdFor<Self>) -> BalanceFor<Self>;
	fn balance(asset: AssetIdFor<Self>, who: AccountIdFor<Self>) -> BalanceFor<Self>;
	// fungibles::InspectEnumerable
	// fn asset_ids() -> Vec<AccountIdFor<Self>>;
	// fn account_balances(who: AccountIdFor<Self>) -> Vec<(AssetIdFor<Self>, BalanceFor<Self>)>;
	}

And we also need a helper function/macro for "client" to easily specify the extension_id which matches the "server" side.
However, these types are concrete types.

XCQ/xcq-extension/tests/extension_executor_works.rs

Lines 113 to 117 in 3c0d9b4

	#[derive(Encode, Decode)]
	enum FungiblesMethod {
	TotalSupply { asset: u64 },
	Balance { asset: u64, who: [u8; 32] },
	}

[indirection42]

Currently, we calculate like this (only consider trait_ident and method_ident):

XCQ/xcq-extension/procedural/src/lib.rs

Lines 169 to 178 in f1af976

	fn calculate_hash(trait_ident: &Ident, trait_items: &[TraitItem]) -> u64 {
	let mut hasher = twox_hash::XxHash64::default();
	trait_ident.hash(&mut hasher);
	for trait_item in trait_items {
	if let TraitItem::Fn(method) = trait_item {
	method.sig.ident.hash(&mut hasher);
	}
	}
	hasher.finish()
	}