fix: avoid faulty duplicate detection

[Mcklmo]

The bug is caused by registering operations with inline struct definitions with varying field names, combined with an empty OperationID.

I noticed this causing a runtime panic on app start. It is no actual security vulnerability, because it is not possible to trigger during app uptime - it only triggers during the initialisation phase. But it is an irritating error to me as a user, as the panic message does not really make sense to me.

I added a test for reproducability. To see the problem in action, just run the tests on your current version, without my fix to the code.

I fixed the error by allowing multiple inline struct definitions with varying field names. What would have caused a duplicate panic before now increments the would be duplicate by one. E.g., the first type will be called "Request", the second "Request1", and so on. That way the behavior is still deterministic and humanly readable in a generated spec. This change does not affect existing code bases because the condition the change has effect on was previously guarded by the runtime panic. I.e., no configuration can have existed that was able to initialise the app with this condition before. Hence, the change will be entirely backwards compatible.

[codecov]

Codecov Report

❌ Patch coverage is 84.61538% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.86%. Comparing base (897fab0) to head (a142116).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
huma.go	80.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #893      +/-   ##
==========================================
- Coverage   92.89%   92.86%   -0.03%     
==========================================
  Files          23       23              
  Lines        4617     4627      +10     
==========================================
+ Hits         4289     4297       +8     
- Misses        271      272       +1     
- Partials       57       58       +1     

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