Implement Stargate message handling/ Queries

[alpe]

// StargateMsg is encoded the same way as a protobof [Any](https://github.com/protocolbuffers/protobuf/blob/master/src/google/protobuf/any.proto).
// This is the same structure as messages in `TxBody` from [ADR-020](https://github.com/cosmos/cosmos-sdk/blob/master/docs/architecture/adr-020-protobuf-transaction-encoding.md)
type StargateMsg struct {
	TypeURL string `json:"type_url"`
	Value   []byte `json:"value"`
}

https://github.com/CosmWasm/wasmvm/blob/0.14-dev/types/msg.go#L154

This can be tested

• Test CosmosMsg::Stargate handling (via reflect contract)
• Test QueryRequest::Stargate handling (via reflect contract)

[alpe]

Same as #388