Add Token/Item entity

[vikiival]

type TokenEntity @entity {
  id: ID!
  blockNumber: BigInt
  collection: CollectionEntity
  nfts: [NFTEntity!] @derivedFrom(field: "token")
  hash: String! @index
  image: String
  media: String
  name: String @index
  updatedAt: DateTime!
  createdAt: DateTime!
  count: Int!
}

The point of TokenEntity is to natively group by NFTs from same collection And same image under one entity with this we can do search, filter super easy. However this require to rapidly change schema
Id should be generated as md5(collection-cid) ?
Name would be either taken from collection of first NFT name stripped from #{number} or _{number}

Also we need to add

type NFTEntity @entity {
  token: TokenEntity!
}