wireproto: port lookup to wire protocol v2
This is pretty straightforward. We don't yet handle errors because we
don't have an error handling mechanism in place yet.
I'm also tempted to fold this into `known`. We'll come back to this
later.
Differential Revision: https://phab.mercurial-scm.org/D3205
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}