Reintroducing LogLikelihood class

[MichaelClerx]

First part of #1705

Breaking change, so upping version number

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (708f287) to head (288e364).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1724   +/-   ##
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  Coverage   100.00%   100.00%           
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  Files           97        97           
  Lines         9776      9787   +11     
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+ Hits          9776      9787   +11     

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[MichaelClerx]

Ran notebook tests locally. Need to fix:

• examples/toy/distribution-rosenbrock.ipynb
• examples/miscellaneous/model-rt-estimation-renewal-equation.ipynb

But others all pass.

More generally: Need to check if toy distributions are likelihoods