ICS20: Update createOutgoingPacket name, signature and sendPacket logic

[mpoke]

• createOutgoingPacket should be renamed to sendTransfer to be consistent with the ibc-go implementation. Plus, the name is currently misleading since the method also sends the packet.
• remove source, destPort, and destChannel from the signature of createOutgoingPacket since they are not needed (i.e., source is computed in the method, while destPort and destChannel can be queried from the channel end (see the ibc-go implementation).
• fix sendPacket call to match ICS4.