ls-remote: print URL when no repo is specified

ls-remote: print URL when no repo is specified

After 9c00de5 (ls-remote: fall-back to default remotes when no remote
specified), when no repository is specified, ls-remote may use
the URL/remote in the config "branch.<name>.remote" or the remote
"origin"; it may not be immediately obvious to the user which was used.

In such cases, print a simple "From <URL>" line to indicate which
repository was used. This message is similar to git-fetch's, and is
printed to stderr to avoid breaking existing scripts that depend on
ls-remote's output behaviour.

It can also be disabled with -q/--quiet.

Modify tests related to falling back on default remotes to check for
this as well, and add a test to check for suppression of the message.

Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>