Rename QueryResponse to QueryResult

[webmaster128]

QueryResponse is analogue to ContractResult but instead of a Response struct with messages, data, attributes, events this only has bytes in the success case. It is the Go counterpart of the Rust ContractResult<Binary>.

In https://github.com/CosmWasm/wasmvm/pull/465/files we clearly see that this lives at the same level as ContractResult.

For the sake of consistency, we should make this a "result" too.