[FEATURE] - Automatically drop empty packages depending on the output of drop_empty_layers_from_dict #1923

Is your feature request related to a problem? Please describe.
Introduced and discussed here: #1912 (comment)

Describe the solution you'd like
Depending on the return value (a member of LAYERS_USED), a package with no data at all should be removed automatically. This was out of scope for the PR, and could be difficult since the package essentially has to remove itself from the model.

Describe alternatives you've considered
Just returning a grid with layer coord with size 0 doesnt work, as that fails during package validation: see this test run where that was tried:

Additional context
Raised as a potential improvement druing development of from #1821