Testing: improve testing features

[athob]

At the moment there is a functional set of data to test the functionalities of wingspipe in the corresponding directory. This can already be used to add a small test of wingspipe init, wingspipe run and wingspipe delete to the github workflow.

Ideally, the testing unit needs to be more thorough: notably, it would need to check:

• if the database has been updated accordingly
• if the wingspipe run did process correctly
  But to be fully complete, the testing unit could also test each object and methods, for which each source file could have its own testing unit.