gitlab-ci: add python script to submit lava jobs

Covert the job submission process to a python script for more robustness and control. allowing easier manipulation of job data.

As a result, it adds retry logic to deal with Infrastructure Errors in LAVA.

_call_proxy() is equipped with a robust retry logic, which I have been using already in the past few weeks in stress testing to run hundreds of jobs.

Signed-off-by: Gustavo Padovan gustavo.padovan@collabora.com