CI: add workflow for automated test of pre/post-processing tools

[EZoni]

In the WarpX repository we have several (mostly Python) pre/post-processing tools that are not tested automatically.

Some are in the Tools directory, others are in the Examples directory, such as, for instance, the plotting scripts in Examples/Physics_applications/beam_beam_collision.

It would be good to have an automated CI workflow that runs these tools to make sure they work and are up-to-date.

[EZoni]

PR #5696 is an example of such a workflow.