Draft: generate-jobs.py: Add a new job generator

This program does not use LQA to generate the job descriptions.

It is capable of finding all the tests for a given image and group them into the adequate template.

This is part of the work in https://phabricator.apertis.org/T7900

Note that lava-submit.py has not been removed, that is because we want other branches that are not updated yet to still work.

The new Job Generator can be tested with the new test structure in tests/apertis-test-cases!407 (merged)