ci: Enable GitLab's Code Quality framework

Enable GitLab's Code Quality which uses Codeclimate with a number of
code checkers.

Changelog: other
Signed-off-by: Robbie Cao <robbie.cao@arm.com>
Signed-off-by: Jingzhao Ni <Jingzhao.Ni@arm.com>
Signed-off-by: Filipe Rinaldi <filipe.rinaldi@arm.com>