libide-projects: Fix license template issues

I found some problems when creating new projects with certain licenses. The MPL 2.0 license is missing from the gresource file, so creating a project with it fails. Meanwhile the LGPL 3.0 short and long licenses are swapped, so projects created with it prepend the full text of the license to the top of the source files.

This merge request fixes those issues, and also updates the links in the GPL family licenses to https in line with the versions currently available on the GNU website.