remote: separate out the remote_find_tracking logic into query_refspecs
Move the body of remote_find_tracking() to a new helper query_refspecs()
that finds a refspec that matches and applies the transformation, but
explicitly takes the list of refspecs, and make remote_find_tracking() a
thin wrapper of it.
Make apply_refspecs() also use query_refspecs().
Signed-off-by: Carlos Martín Nieto <cmn@elego.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>