[FEATURE] Unified Tokenlist / Pricing and Balance API

[tombeckenham]

Feature

We'd like to introduce a unified tokenlist / pricing and balance API then refactor the client code on all 3 clients to use this new function

Expected Outcomes

• A single API call should replace at least 3 calls on the client side to compile this information
• There should be an API for EVM and an API for Cadence / Child accounts
• The API should take an address, network, and currency as parameters. It's ok to only support USD as the currency for the moment.
• The API should return coin balances as fixed strings with the correct number of decimal places. It should exactly match what is returned by fcl.
• The API should calculate the total balance in the currency supplied for, return all the information needed to send and / or display tokens.
• The API should return the maximum available balance for each of the tokens as well - in the case of Flow for a main Cadence account this should be the amount of flow that is available to send - that isn't used for storage.
• It should return the information about decimals, and any information needed to send the token - address logo etc.

Platforms

• Server (FRW-Web-Next)
• iOS
• Android
• Extension

Screenshots

The API should provide everything needed for these screen elements - and to transfer tokens: