Investigate exposing an API which implements IBC gRPC queries

[plafer]

Chains that use ibc-rs must also implement gRPC query endpoints for relayers to use (e.g. in a manner similar to basecoin-rs to be compatible with hermes).

We should keep in mind however that the go relayer handles gRPC endpoints differently from hermes. Whereas hermes expects actual gRPC endpoints to be exposed, the go relayer encodes gRPC queries as ABCI queries (as brought up by @avahowell).

The point being that we should write an ADR and make sure that our design is compatible with chains that use the go relayer as well as chains that use hermes, before we start implementing anything.

As suggested by @keppel in the community call.