Fix OpenAPI hierarchy

[elic-eon]

🤔 Why?

APIs without tags have empty hierarchy but they should belongs to top-level OpenAPI hierarchy

https://app.shortcut.com/metaphor-data/story/29745

🤓 What?

• Fix directories logic

🧪 Tested?

Add unit tests.

☑️ Checks

• My PR contains actual code changes, and I have updated the version number in pyproject.toml.

[usefulalgorithm]

👍

[github-actions]

☂️ Python Coverage

current status: ✅

Overall Coverage

Lines	Covered	Coverage	Threshold	Status
13438	11999	89%	85%	🟢

New Files

No new covered files...

Modified Files

File	Coverage	Status
metaphor/openapi/extractor.py	93%	🟢
TOTAL	93%	🟢

updated for commit: dd6e00b by action🐍

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.29%. Comparing base (cc34d58) to head (dd6e00b).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1037   +/-   ##
=======================================
  Coverage   89.28%   89.29%           
=======================================
  Files         206      206           
  Lines       13438    13438           
=======================================
+ Hits        11998    11999    +1     
+ Misses       1440     1439    -1     

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