Support staking queries

[ethanfrey]

Ensure all metadata is in the contracts.
Provide adaptor for the gRPC clients.
Ensure we have all info needed for CosmWasm query request support as well

Builds on https://github.com/confio/tgrade-contracts/issues/280 Please comment there for any other info needed by the sdk. Especially for slashing/jailing.

Update:
This task is about implementing a new StakingQuerier query handlers that works with PoE contracts, so that contracts can query data using the same query api.
Some queries are implemented already in https://github.com/confio/tgrade/blob/main/x/poe/wasm/query_plugin.go#L25

[daniellarita]

@alpe can you see if this is still relevant

[alpe]

Implementing the query is not state breaking itself but the code needs to be rolled out to all validators before it can be used. Consumer of this query is the valset contract.

[pinosu]

Closing the issue because it is already implemented.