[BUG] Properly define public api

[raphaelreinauer]

According to PEP8:

To better support introspection, modules should explicitly declare the names in their public API using the all attribute. Setting all to an empty list indicates that the module has no public API.

https://peps.python.org/pep-0008/#public-and-internal-interfaces

E.g.

giotto-deep/gdeep/utility/__init__.py

Line 11 in f62b2ef

'_inner_refactor_scalars', # This should be here

The _inner_refactor_scalars method should not be in the all
Maybe there are more issues like that, it's the only one I encountered.

[matteocao]

I just went though all the __init__ files and found also this:

giotto-deep/gdeep/search/__init__.py

Line 14 in bb0c449

'_benchmarking_param',

I corrected all of them.