Enable test checking in Gitlab CI pipelines

Define a base job that could be modified by downstream projects
that audits its pipeline test result based on a JSON test list,
EXPECTED_TESTS_FILE and will pass/fail the job based on the
result.

Changelog: feature
Signed-off-by: Philip Puk <philip.puk@arm.com>
Signed-off-by: Adam Johnston <adam.johnston@arm.com>