Link roles, aka :zephyr_file: and :zephyr_raw: use a repo's git describe
information to create links but the baseurl is fixed to the upstream
repo. This breaks links created in repos that are forks located
somewhere else.
This commits tries to get the baseurl from west if available so it will
work correctly for forks. If fallbacks to the upstream repo if no
information can be gathered by West, or West is not available.
Signed-off-by: Fabio Utzig <fabio.utzig@nordicsemi.no>
ae8dd14887