ABCI Merkle Proof struct does not match Go counterpart

[romac]

@ancazamfir uncovered what we think is a discrepancy between the way ABCI Merkle proofs are represented in this crate vs the Go implementation.

The AbciQuery datatype into which ABCI responses are deserialized* carries an optional Proof, which is defined in this crate as a wrapper around a bytevector serialized as a hex-encoded string, whereas the corresponding struct in the Go code is defined as an actual struct with proof ops etc.

It is thus currently not possible to properly deserialize the result of ABCI queries when those carry a proof, as shown in the tests Anca included in her PR implementing a consensus state query for ibc-rs.

* We should perhaps find a better name for that struct, since it is used both for queries and their responses. Or perhaps the issue stems from the fact that those should be different datatypes?

[tarcieri]

I'm guessing this is another v0.33 incompatibility? (see #184)

[tomtau]

ABCI Proof was structured that way before 0.33: https://github.com/tendermint/rust-abci/blob/aa163393f139b971f7935ad6afac4f542e1bb016/src/messages/merkle.rs

I guess it should be fine once the types are generated from canonical protobuf definitions
ref: #29 (comment)

[ancazamfir]

Fixed in #206, in tendermint/v0.33 branch. Thanks @liamsi