Refactor AssetId

[clearloop]

Issue summary

Currently, we have numeric AssetId in pallet-asset-index, should we refactor it into another type?

PINT/pallets/asset-index/src/lib.rs

Line 94 in 49ce268

type AssetId: Parameter + Member + From<u32> + Copy;

Other information and links

• Acala/primitives/Currency

• polkadot/xcm/xcm-executor

• Integrate chainlink feed AcalaNetwork/Acala#1073

• feat(asset-index): add AssetMetadata #105

• Refactor AssetId in pallet-asset-index as enumeration #102

[mattsse]

There are several options, as discussed in #105 our asset identifiers are dynamic, meaning, something like,

enum AssetId {
  Saft(id),
  Liquid(id)
}

does not really work, because a saft asset id will eventually become a liquid asset.

I think we should stick with simple numeric types, but accept additional AssetMetadata when creating assets and store that in the registries.