ref-filter: allow porcelain to translate messages in the output

ref-filter: allow porcelain to translate messages in the output

Introduce setup_ref_filter_porcelain_msg() so that the messages used in
the atom %(upstream:track) can be translated if needed. By default, keep
the messages untranslated, which is the right behavior for plumbing
commands. This is needed as we port branch.c to use ref-filter's
printing API's.

Written-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Mentored-by: Christian Couder <christian.couder@gmail.com>
Mentored-by: Matthieu Moy <matthieu.moy@grenoble-inp.fr>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>