wireprotov2: decode responses to their expected types Callers of established wire protocol commands expect the response from that command to be decoded into a data structure. It's not very useful if callers get back a stream of bytes and don't know how they should be interpreted - especially since that stream of bytes varies by wire protocol and even the transport within that protocol version. This commit establishes decoding functions for various command responses so callers of those commands get the response type they expect. In theory, this should make the version 2 HTTP peer usable for various operations. But I haven't tested to confirm. Differential Revision: https://phab.mercurial-scm.org/D3381