Add pdf() and logpdf() for Distortions

[lrnv]

fixes #345

should add pdf and logpdf capacities to all distortions in the package, including generic ones.

[codecov]

Codecov Report

❌ Patch coverage is 93.85965% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.90%. Comparing base (fdd219b) to head (b2bf1a9).

Files with missing lines	Patch %	Lines
src/Conditioning.jl	57.14%	3 Missing ⚠️
...ateDistribution/Distortions/HistogramDistortion.jl	81.81%	2 Missing ⚠️
...UnivariateDistribution/Distortions/NoDistortion.jl	0.00%	1 Missing ⚠️
...iateDistribution/Distortions/PlackettDistortion.jl	93.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #360      +/-   ##
==========================================
- Coverage   77.92%   77.90%   -0.03%     
==========================================
  Files          84       83       -1     
  Lines        4988     5024      +36     
==========================================
+ Hits         3887     3914      +27     
- Misses       1101     1110       +9     

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