Test checking script for Gitlab CI pipeline jobs

The purpose of the script is to audit test results from a given
CI pipeline and produce pass/fail results based on a machine
readable list of tests which are expected to pass.

The script will first read the list of expected pass tests from
a json file. Also, relying on the predefined CI variables
and gitlab-python module to access the pipeline test reports.
By comparing list of expected pass test and passed tests extracted
from actual test reports, the script will print "FAIL" to stderr if
there are missing tests that are expected to pass or "PASS" if all
expected tests passed.

Signed-off-by: Philip Puk <philip.puk@arm.com>