Add data query for resolvers by manager

[ryanchristo]

Summary

We currently have query resolvers by url and query resolvers by content hash. As a resolver manager for multiple resolvers, I should be able to query all resolvers by manager.

Problem Definition

A resolver manager for multiple resolvers should be able to query all resolvers managed by their account.

Proposal

Add QueryResolversByManager proto definition, implement the query with tests, and add a CLI command.

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