debugcommands: support connecting to HTTP peers Now that we have the plumbing for logging socket activity, let's hook it up to `hg debugwireproto` so we can collect low-level activity on sockets. The new code is a bit incomplete. But it is better than nothing: `hg debugwireproto` is still heavily evolving. The added test demonstrates some interesting behavior. For example, we're calling socket.makefile() and doing I/O on that. TIL. We're also sending an "Accept-Encoding: identity" request header. Differential Revision: https://phab.mercurial-scm.org/D2726