gitea: Fix API URL when "owner/project" is prefixed in origin URL path
Some gitea origins can have non standard URLs in the form below:
(scheme)://(netloc)/(prefix)/(owner)/(project).
Previous loader implementation could not correctly compute API URLs from such origin URLs so ensure it can.
Fixes #4 (closed)
Fixes SWH-LOADER-METADATA-Y
Edited by vlorentz