Use gRPC to query Cosmos SDK chain states

[soareschen]

Crate

relayer

Summary

This is a follow up to #1048. Since we can do height-based gRPC query through the x-cosmos-block-height parameter, we can refactor other queries such as query_channel to use the gRPC endpoints instead of the Tendermint RPC endpoint.

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[adizere]

We'll be able to increasingly use gRPC now with the recent changes adding gRPC support for ABCI queries in the SDK https://github.com/cosmos/cosmos-sdk/pull/11642

[plafer]

Relevant comment by @ancazamfir.