On-chain registry for token metadata

[chuck-h]

What

A contract with tables that hold metadata (e.g. graphical logo, descriptive name) for each cryptotoken used in the Seeds ecosystem. The contract data provides a shared registry readily available to any wallet app or other application.

Why

• Users should see consistent UI features for each token across applications, to minimize confusion
• Adding new tokens should be logistically simple, as we expect DHOs and affiliates to be creating new tokens on a regular basis. Executing an action on this contract is simpler than updating data structures within the codebase of each application.
• A human vetting role is needed to prevent token symbols & descriptions which are accidentally (or intentionally) confusing from entering the Seeds ecosystem

How

The contract has a "submit" action which contains fields uniquely identifying the token (e.g. HUSD token from husd.hypha contract on Telos mainnet) and extensible JSON data carrying metadata; this creates an on-chain table entry for the token. A subsequent human vetting process results in the token and metadata being accepted for use. The contract allows for granularity in acceptance domains (e.g. a token might appear on seeds-swaps but not in the Passport)

[chuck-h]

Pull request https://github.com/JoinSEEDS/seeds-smart-contracts/pull/420

[chuck-h]

We need a schema for the json metadata.