Including building, testing, code coverage reporting and documentation
uploads to GitLab pages. The documentation and code coverage reports
will appear at:

https://pwithnall.pages.gitlab.gnome.org/libglib-testing/docs/
https://pwithnall.pages.gitlab.gnome.org/libglib-testing/coverage/



Signed-off-by: Philip Withnall <withnall@endlessm.com>