Add plot ecdf pit plot

[aloctavodia]

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📚 Documentation preview 📚: https://arviz-plots--173.org.readthedocs.build/en/173/

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 15.27778% with 61 lines in your changes missing coverage. Please review.

Project coverage is 73.90%. Comparing base (45dc887) to head (cc00f59).

Files with missing lines	Patch %	Lines
src/arviz_plots/plots/ecdfplot.py	14.08%	61 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #173      +/-   ##
==========================================
- Coverage   75.01%   73.90%   -1.11%     
==========================================
  Files          33       34       +1     
  Lines        3818     3890      +72     
==========================================
+ Hits         2864     2875      +11     
- Misses        954     1015      +61     

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