scripts/convert-srcuri: Update SRC_URI conversion script to handle github url changes

Github are dropping support for git:// protocol fetching. Update the script
to learn about corner cases found in the previous conversion and
support remapping the github urls as needed too.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit e59fe827)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>