[BUG] CodegenProperty#isInherited not set right

[devhl-labs]

Some properties do not have isInherited set correctly. See modules\openapi-generator\src\test\resources\3_0\allOf.yaml Child properties Type, LastName, FirstName will have isInherited set to false when it should be true. This is in csharp-netcore, any library.

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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[ahmednfwela]

I have also encountered this problem on #12295 , will make a PR to solve it

[devhl-labs]

Fantastic. I have a hot fix in the CSharpNetCoreClientCodegen that can be removed once this is fixed. The url for this issue is in the code.