.arcconfig

lfs: use the localstore download method to transfer from remote stores

Both gitlfsremote and file based remotes benefit from not requiring the whole
file in memory (though the whole file is still loaded when passing through the
revlog interface).  With a method specific to downloading from a remote store,
the misleading 'use hg verify' hint is removed.  The behavior is otherwise
unchanged, in that a download from both remote store types will yield a copy of
the blob via util.atomictempfile.

There's no response payload defined for the non 'download' actions, but the
previous code attempted to read the payload in this case anyway.  This
refactored code made that more obvious, so any payload is printed as a debug
message, just in case.

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