MsgBridge defines the Bridge message type.
relayer is the address that signs the message.
destination_chain defines the chain which this will be relayed to.
warden_contract_address defines the warden contract that GMP is calling.
destination_contract_address defines the destination contract that warden is calling.
destination_contract_calldata defines the command to call.
token determines the IBC token that the user wants to relay via GMP.
A successful response.