Add a method to parse IbcSendPacketResponse protobuf bytes

[larry0x]

This response type has been introduced to wasmd, but there isn't a handy function to parse it: CosmWasm/wasmd#1154

[webmaster128]

You can do that with Bufany now (untested):

use anybuf::Bufany;

let deserialized = Bufany::deserialize(&data).map_err(|_e| StdError::generic("could not parse response data")?;
let sequence = deserialized.uint64(1).ok_or_else(StdError::generic("could not get sequence")?;