Support general nonnil->nonnil function contract, i.e., having a single nonnil but any numbers of any, e.g. contract(_,nonnil->nonnil,_)

[zzqatuber]

Support general nonnil->nonnil function contract, i.e., having a single nonnil but any numbers of any, e.g. contract(,nonnil->nonnil,).

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 85.55133% with 76 lines in your changes missing coverage. Please review.

Project coverage is 87.55%. Comparing base (6b5d588) to head (881b950). Report is 98 commits behind head on main.

Files	Patch %	Lines
assertion/function/functioncontracts/infer.go	85.40%	42 Missing and 5 partials :warning:
assertion/function/functioncontracts/analyzer.go	84.78%	10 Missing and 4 partials :warning:
...nction/functioncontracts/function_contracts_map.go	78.94%	6 Missing and 2 partials :warning:
assertion/function/analyzer.go	78.12%	6 Missing and 1 partial :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #41      +/-   ##
==========================================
- Coverage   87.62%   87.55%   -0.08%     
==========================================
  Files          52       54       +2     
  Lines        8080     8547     +467     
==========================================
+ Hits         7080     7483     +403     
- Misses        853      906      +53     
- Partials      147      158      +11     

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[yuxincs]

We have made significant changes to NilAway since this PR was originally created, so I'm closing this PR as it's really hard to rebase the changes onto the current main.

We'll continue the work (with proper attribution) by using this PR as a reference.