.gitlab-ci.yml: add trigger per type of job

.gitlab-ci.yml: add trigger per type of job

Currently the user has 2 sets of jobs that can be triggered on a GitLab
pipeline.
 - to trigger all defconfigs, all runtime tests and all check-* jobs:
   $ git tag <name>
   $ git push gitlab <name>                     # currently 260 jobs
 - to trigger only the check-* jobs:
   $ git push gitlab HEAD:<name>                # currently   4 jobs

This is not much versatile, so the user ends up hand-editing the
.gitlab-ci.yml in order to trigger some subsets, even the common ones,
for instance all runtime tests.

Add 2 more subsets that can be triggered based on the name of the
branch pushed.
 - to trigger all defconfigs and all check-* jobs:
   $ git push gitlab HEAD:<name>-defconfigs     # currently 192 jobs
 - to trigger all runtime tests and all check-* jobs:
   $ git push gitlab HEAD:<name>-runtime-tests  # currently  72 jobs

Signed-off-by: Ricardo Martincoski <ricardo.martincoski@gmail.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>