Cosmos-sdk: Finish migration to grpc in IBC

[colin-axner]

Summary

Now that client state and consensus states have been migrated to proto, the querier in IBC should be removed and the client/consensus state grpc functions should be added.

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[cwgoes]

Also, sounds like we need to figure out how proofs will work with gRPC queries/queriers.

[colin-axner]

So for the short term I'm going to add a ABCI query helper func similar to the one in the testing package to ensure the +1 only happens once. I'll probably do a pr which renames client/utils to client/query with query.go. This file will contain functions that basically act as a wrapper around gRPC calls and use the helper func to inject a proof/proof height into the queries.

I think it is quite redundant to do a gRPC query and an ABCI query in the same call, so I will also open issue around my thoughts on how to handle adding proofs from within gRPC calls and at least get the conversation started around this issue. Though it isn't strictly necessary for 1.0 so I think its implementation is not high priority unless it seems to be relatively easy

cc/ @fedekunze @AdityaSripal

[colin-axner]

opened #7036

[fedekunze]

Unrelated to the comment above, but I think we should drop the support for the legacy REST server and just use gRPC + gateway for REST-like queries.

[colin-axner]

Unrelated to the comment above, but I think we should drop the support for the legacy REST server and just use gRPC + gateway for REST-like queries.

I agree :+1: