Add hook points for error-returning functions that make arguments nonnil

[yuxincs]

This pull request introduces support for recognizing and modeling the effect of trusted functions whose error return, when nil, guarantees that a specific pointer argument is non-nil. The primary example handled is json.Unmarshal(data, &v), where a successful unmarshal ensures that v is non-nil. This is achieved by adding a new analysis hook, integrating it into the assertion effect system, and providing comprehensive tests.

Fixes #342

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.26%. Comparing base (ac4de95) to head (9014ccc).

Files with missing lines	Patch %	Lines
...ertion/function/assertiontree/rich_check_effect.go	88.88%	2 Missing and 2 partials ⚠️
hook/error_return.go	66.66%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #426      +/-   ##
==========================================
- Coverage   87.29%   87.26%   -0.03%     
==========================================
  Files          73       74       +1     
  Lines        8396     8444      +48     
==========================================
+ Hits         7329     7369      +40     
- Misses        872      876       +4     
- Partials      195      199       +4     

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[github-actions]

Golden Test

Note

✅ NilAway errors reported on standard libraries are identical.

2187 errors on base branch (main, ac4de95)
2187 errors on test branch (1b163db)