Add comp_basis_encoder to models.encodings

[renatomello]

Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (51a0e92) 100.00% compared to head (ab8e039) 100.00%.

❗ Current head ab8e039 differs from pull request most recent head bfb3ae3. Consider uploading reports for the commit bfb3ae3 to get more accurate results

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #1165   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           68        68           
  Lines         9883      9906   +23     
=========================================
+ Hits          9883      9906   +23     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[BrunoLiegiBastonLiegi]

Maybe add a couple of words about this and the other encoders we already have? I remember I was trying to use them some time ago but I had a hard time understanding how to use them. A small example of how to encode data into circuits might help.