Added activations in tests

[BrunoLiegiBastonLiegi]

Adds activations similar to the one used in the notebook #49.
Various fixes to the tests are also introduced.
Makes BinaryEncoding a layer of RX in practice and gets rid of the 1/0 check and branching.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.85%. Comparing base (3e52004) to head (04632be).
Report is 15 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #55       +/-   ##
===========================================
+ Coverage   61.06%   78.85%   +17.78%     
===========================================
  Files          11       11               
  Lines         488      487        -1     
===========================================
+ Hits          298      384       +86     
+ Misses        190      103       -87     

Flag	Coverage Δ
unittests	78.85% <100.00%> (+17.78%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/qiboml/models/encoding.py	95.23% <100.00%> (-0.12%)	⬇️
src/qiboml/models/pytorch.py	98.59% <ø> (+57.74%)	⬆️

... and 3 files with indirect coverage changes