.arcconfig

lfs: emit a status message to indicate how many blobs were uploaded

Previously, there was a progress bar indicating the byte count, but then it
disappeared once the transfer was done.  Having that value stay on the screen
seems useful.  Downloads are done one at a time, so hold off on that until they
can be coalesced, to avoid a series of lines being printed.  (I don't have any
great ideas on how to do that.  It would be a shame to have to wrap a bunch of
read commands to be able to do this.)

I'm not sure if the 'lfs:' prefix is the right thing to do here.  The others in
the test are verbose/debug messages, so in the normal case, this is the only
line that's prefixed.

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