bundle: framework for options before bundle file

bundle: framework for options before bundle file

Make it possible for any of the git-bundle subcommands to include
options:
- before the sub-command
- after the sub-command, before the bundle filename

There is an immediate gain in support for help with all of the
sub-commands, where 'git bundle list-heads -h' previously returned an
error.

Downside here is an increase in code duplication that cannot be
trivially avoided short of shared global static options.

Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>