[BUG] [Python] PythonSrcRoot should be apart of import when in use.

Created by: tray2100

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

If you're dropping OpenAPI into python project you may decide to leverage pythonSrcRoot to have the generated code conform to your existing folder structure. The problem, though, is since the generated code doesn't know the true module root, the imports become a pain and don't work well. We need to introduce the ability to include the pythonSrcRoot into the import namespace.

openapi-generator version

5.1.1

Related issues/PRs

Suggest a fix

The fix here would be to introduce a new generator config value that would allow users to specify they want the pythonSrcRoot included in Imports then have the generator modify packageName accordingly.