[Feature]: expose keys for key based queries

[tac0turtle]

Summary

AbciQuery and KVQuery are useful for getting data and doing proofs. There is not a clean way to get the keys out without relying on modules or manually reading the code. We should offer a way to see all keys available on a chain that can be queried through the abciQuery system.

Problem Definition

No response

Proposed Feature

With the adoption of collections and the use of schema we should be able to see the keys being used. If we offered an endpoint to see all the keys it would be simpler to see what is available on chain