query ClientState given client id

[ebuchman]

Given a client id, query the ClientState object.

Note ClientState is an interface, instantiated by the concrete type of client (eg. a Tendermint client). So a real result here will involve Tendermint-specific data structures.

Note this also doesn't have a protobuf file yet, it's defined as a Go struct. This may be blocking for now (since it means we're dealing with Amino-encoded validators ...)

Opened a related issue on the SDK: cosmos/cosmos-sdk#6736

ABCIQuery.Path = store/ibc/key
ABCIQuery.Data = clients/{identifier}/clientState

[ebuchman]

This is blocked on the SDK upgrading to use the tendermint v0.34 release (currently a Release Candidate), but that should probably happen shortly.

[ancazamfir]

Finished after all the protobuf updates, tm releases, informalsystems/hermes#235, informalsystems/hermes#292, cosmos/ibc-rs#106.