[Experimental] Introduce ImplicitBPRWrapper model

[chezou]

Description

Address #132

As a first step, don't support features at this moment since it requires to additional design for CPU implementation because CPU BPR class is fully Cythonized.

While I tried to keep deterministic for unit tests, BPR updates random states every fit, so I gave up some tests. Some tests may flakey.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Optimization

How Has This Been Tested?

Before submitting a PR, please check yourself against the following list. It would save us quite a lot of time.

• Have you read the contribution guide?
• Have you updated the relevant docstrings? We're using Numpy format, please double-check yourself
• Does your change require any new tests?
• Have you updated the changelog file?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (9b3992e) to head (5f3211d).
Report is 86 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##              main      #232     +/-   ##
===========================================
  Coverage   100.00%   100.00%             
===========================================
  Files           45        60     +15     
  Lines         2242      3970   +1728     
===========================================
+ Hits          2242      3970   +1728     

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