Reexport other pointwise density functions

[penelopeysm]

Although arguably pointwise_loglikelihoods is the most important one, it seems a bit weird that we don't re-export the other two as well.

[github-actions]

Turing.jl documentation for PR #2812 is available at:
https://TuringLang.github.io/Turing.jl/previews/PR2812/

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.23%. Comparing base (b6fa993) to head (dd82ac1).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2812   +/-   ##
=======================================
  Coverage   85.23%   85.23%           
=======================================
  Files          22       22           
  Lines        1483     1483           
=======================================
  Hits         1264     1264           
  Misses        219      219           

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