State Proofs: Verify proofs by CLI

[ashcherbakov]

After migration to the latest cosmos-sdk, the CLI doesn't verify state proofs for queries to store even if they are returned. See cosmos/cosmos-sdk#6563.
We need to change it, so that CLI verifies state proofs if they are returned by a query.
Consider

• Contribution to https://github.com/cosmos/cosmos-sdk/tree/master/client
• The following needs to be verified for every state proof:
  • Merkle Proof (see https://github.com/cosmos/cosmos-sdk/blob/master/store/rootmulti/proof.go)
  • State signatures via Tendermint's light client. See https://github.com/tendermint/tendermint/tree/master/light

Please note, that

• Cosmos CLI queries don't return state proofs by default , so this change doesn't make much sense without implementing State Proofs: Return proofs in queries made by CLI #183 as well.
• Only single value queries (that is quering items stored in Store directly) will be supported. For example get-model will have a state proof returned, while get-all-models will not.
  Multi value proofs support is a separate task: State Proofs: Light client for lists #34.