[python] add circular reference import

[fa0311]

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Pydantic v2 has made significant changes to the specifications regarding the reconstruction of models required for circular references.
This requires the construction of a very complex referencing algorithm to resolve.
I hope to have those issues resolved by the 7.1.0 release of openapi-generator. Because importing circular references is needed by many people.
I propose these temporary fixes because I do not want to spend time building a complex referencing algorithm.

I would prefer not to use raise_errors, but it is very useful as a temporary implementation.

@fa0311 @multani

[fa0311]

Maybe conflicts with #16809

[multani]

Looks good to me, thanks for the fix!

[multani]

@wing328 I think we can merge this one 👍