lfs: add "bytes" as the unit to the upload/download progress bar

Facebook also passes `util.bytecount()` as a pretty formatter here, but our
progress bar doesn't support that.

Differential Revision: https://phab.mercurial-scm.org/D7872

hgext/lfs/blobstore.py

@@ -588,7 +588,9 b' class _gitlfsremote(object):'
         else:
             oids = transfer(sorted(objects, key=lambda o: o.get(b'oid')))
 
-        with self.ui.makeprogress(topic, total=total) as progress:
+        with self.ui.makeprogress(
+            topic, unit=_(b"bytes"), total=total
+        ) as progress:
             progress.update(0)
             processed = 0
             blobs = 0