Separate tests in jobs to run faster

[AlexandreMary]

Currently a number of tests are gathered in single jobs, either through families or in loops (model, geometry, oops/CNT0, or by compilation flavour).
As a result the jobs, which sequentially run each test, take a long time to execute, which is not optimal in development mode.
The proposal here, and already submitted to a large extent in PR #26, is to split them in more, smaller jobs.

To do in sync with #11