repository: formalize wire protocol interface
There are a well-defined set of commands constituting the wire
protocol. Interaction with these and methods for calling them in
batches are exposed via methods on peer instances.
Let's formalize support for these features in abstract classes.
The command parts come from the existing wireproto.wirepeer class.
The batch methods come from peer.peerrepository.
Ample documentation has been added as part of defining the interfaces.
# no-check-commit
Differential Revision: https://phab.mercurial-scm.org/D333
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}