wic: beautify 'wic help'

wic: beautify 'wic help'

The Wic help returned to the user is unreadable.

Use a custom ArgumentParser to override argparse help message.

change help message as suggest in
https://bugzilla.yoctoproject.org/show_bug.cgi?id=12205
[YOCTO #12205]

changes applies to 'wic help', 'wic -h', 'wic --h' and 'wic --help'

Signed-off-by: Chee Yang Lee <chee.yang.lee@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>