Implement Inverse CDF dispatch functions

[ricardoV94]

No description provided.

[ricardoV94]

Latest Aesara release is causing tests/test_scan.py::test_initial_values to fail:
https://github.com/aesara-devs/aeppl/runs/6918324742?check_suite_focus=true

[brandonwillard]

After creating an issue for that unrelated, failing test, we can mark the test as xfail in this PR.

[codecov]

Codecov Report

Merging #147 (95e1cb8) into main (8f65562) will decrease coverage by 0.10%.
The diff coverage is 86.95%.

@@            Coverage Diff             @@
##             main     #147      +/-   ##
==========================================
- Coverage   94.88%   94.78%   -0.11%     
==========================================
  Files          12       12              
  Lines        1780     1802      +22     
  Branches      263      264       +1     
==========================================
+ Hits         1689     1708      +19     
- Misses         51       53       +2     
- Partials       40       41       +1     

Impacted Files	Coverage Δ
aeppl/logprob.py	98.02% <86.36%> (-0.78%)	⬇️
aeppl/truncation.py	98.27% <100.00%> (ø)

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[brandonwillard]

Just some minor updates; otherwise, this looks good.