builtin-remote: Show push urls as well

builtin-remote: Show push urls as well

Teach builtin remote to show push urls also when asked to
"show" a specific remote.

This improves upon the standard display mode: multiple specified "url"s
mean that the first one is for fetching, all are used for pushing. We
make this clearer now by displaying the first one prefixed with "Fetch
URL", and all "url"s (or, if present, all "pushurl"s) prefixed with
"Push  URL".

Example with "one" having one url, "two" two urls, "three" one url and
one pushurl (URL part only):

* remote one
  Fetch URL: hostone.com:/somepath/repoone.git
  Push  URL: hostone.com:/somepath/repoone.git
* remote two
  Fetch URL: hosttwo.com:/somepath/repotwo.git
  Push  URL: hosttwo.com:/somepath/repotwo.git
  Push  URL: hosttwobackup.com:/somewheresafe/repotwo.git
* remote three
  Fetch URL: http://hostthree.com/otherpath/repothree.git
  Push  URL: hostthree.com:/pathforpushes/repothree.git

Also, adjust t5505 accordingly and make it test for the new output.

Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>