Add BetaBinomial distribution

[aleicazatti]

Description

WIP because pz.quartile function didn't work with this distribution, yet to find out why

Checklist

• Code style is correct (follows pylint and black guidelines)
• Includes new or updated tests to cover the new feature
• New features are properly documented (with an example if appropriate)
• Includes a sample plot to visually illustrate the changes (only for plot-related functions)

[codecov-commenter]

Codecov Report

Merging #200 (9010a7b) into main (23a7fef) will increase coverage by 0.22%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #200      +/-   ##
==========================================
+ Coverage   83.16%   83.38%   +0.22%     
==========================================
  Files          26       26              
  Lines        2697     2733      +36     
==========================================
+ Hits         2243     2279      +36     
  Misses        454      454              

Impacted Files	Coverage Δ
preliz/internal/distribution_helper.py	97.56% <ø> (ø)
preliz/tests/test_maxent.py	100.00% <ø> (ø)
preliz/tests/test_mle.py	100.00% <ø> (ø)
preliz/tests/test_quartile.py	100.00% <ø> (ø)
preliz/distributions/__init__.py	100.00% <100.00%> (ø)
preliz/distributions/discrete.py	97.41% <100.00%> (+0.39%)	⬆️
preliz/tests/test_distributions.py	100.00% <100.00%> (ø)

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