.arcconfig

sshpeer: add support for request tracing

The new 'devel.debug.peer-request' option now also display some information
about request going through ssh peer.

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}