Merge branch 'js/for-each-ref-remote-name-and-ref'

The "--format=..." option "git for-each-ref" takes learned to show
the name of the 'remote' repository and the ref at the remote side
that is affected for 'upstream' and 'push' via "%(push:remotename)"
and friends.

* js/for-each-ref-remote-name-and-ref:
for-each-ref: test :remotename and :remoteref
for-each-ref: let upstream/push report the remote ref name
for-each-ref: let upstream/push optionally report the remote name

diff --cc Documentation/git-for-each-ref.txt
Simple merge

diff --cc ref-filter.c
Simple merge

diff --cc remote.c
Simple merge

diff --cc t/t6300-for-each-ref.sh
Simple merge