[python] Support "default" responses in python client

[EraYaN]

This makes sure that the python client actually respects the default response type instead of returning None. Making is much more useful.

Would fix #11793 for the python generator.

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@cbornet (2017/09) @tomplus (2018/10) @krjakbrjak (2023/02) @fa0311 (2023/10)

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Summary by cubic

Honor OpenAPI default responses in Python clients by deserializing them when no explicit status mapping matches (including invalid or out-of-range statuses). Fixes #11793.

• Bug Fixes
  • Fallback to 'default' only when no exact or Xxx class match exists, status is missing/invalid/out-of-range, and 'default' is defined in the map.
  • In partial_api.mustache, emit 'default' in _response_types_map for wildcard responses only when a schema is present.
  • Regenerated Python samples and petstore clients to include the 'default' mapping (aiohttp, httpx, httpx-sync, sync, lazyImports, echo_api, legacy-model-dictionaries).

^{Written for commit a450ff9. Summary will update on new commits.}

[cubic-dev-ai]

All reported issues were addressed across 20 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[EraYaN]

I have added a small comment, it's essentially an inverse condition of the previous two statements