[Python] Add function to get list of allowed enum vars

Description

We have a lot of enums defined in our backend. We have a small UI that shows these enums as a dropdown. The problem we face is whenever we update the enums on our backend. We have to update the frontend code. If swagger codegen can provide the enum values as a list we can return that in an API for frontend to populate these values or use this function to render it in django forms.

For example:

Consider this class

https://github.com/swagger-api/swagger-codegen/blob/b7ba9623a6fa8d9d352f4d8f9adea68119d71721/samples/client/petstore/python/petstore_api/models/outer_enum.py#L29-L31

It has enums placed, approved, delivered. But there is no way for me to get these values as a list at the moment.

Swagger-codegen version

2.4.8

Suggest a fix/enhancement

Add a function that returns the list of enum vars.

Start with the generated Python model shown in samples/client/petstore/python/petstore_api/models/outer_enum.py around lines 29–31, then trace the template or generator input that produces its enum definitions. Confirm how the allowed values should be exposed for generated models and add coverage for the outer_enum example. Done means callers can retrieve placed, approved, and delivered as a list.