Extend C implementation of psi to support negative inputs

[Abhinav-Khot]

Description

Modified the C implementation of psi to handle negative inputs too using the reflection formula for the digamma function. Added tests to verify the functionality.

Related Issue

• Closes C implementation of psi doesn't handle negative inputs #1444
• Related to #

Checklist

• Checked that the pre-commit linting/style checks pass
• Included tests that prove the fix is effective or that the new feature works
• Added necessary documentation (docstrings and/or example notebooks)
• If you are a pro: each commit corresponds to a relevant logical change

Type of change

• New feature / enhancement
• Bug fix
• Documentation
• Maintenance
• Other (please specify):

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📚 Documentation preview 📚: https://pytensor--1523.org.readthedocs.build/en/1523/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.04%. Comparing base (2a7f3e1) to head (90714db).
Report is 212 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1523      +/-   ##
==========================================
+ Coverage   81.99%   82.04%   +0.04%     
==========================================
  Files         188      231      +43     
  Lines       48553    52365    +3812     
  Branches     8673     9217     +544     
==========================================
+ Hits        39812    42963    +3151     
- Misses       6579     7094     +515     
- Partials     2162     2308     +146     

Files with missing lines	Coverage Δ
pytensor/scalar/math.py	87.77% <100.00%> (+0.01%)	⬆️

... and 114 files with indirect coverage changes

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