RegisterCounterpartyPayee defines a rpc handler method for MsgRegisterCounterpartyPayee RegisterCounterpartyPayee is called by the relayer on each channelEnd and allows them to specify the counterparty payee address before relaying. This ensures they will be properly compensated for forward relaying since the destination chain must include the registered counterparty payee address in the acknowledgement. This function may be called more than once by a relayer, in which case, the latest counterparty payee address is always used.