Allow the OpenApiOperation be placed as a Paths or a Webhook

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Is your feature request related to a problem? Please describe the problem.

I'm trying to use existing `AddOpenApiOperationTransformer` extension to tell the operation whether it should be stored in the default paths or in the webhooks section of the document since they are all PathitemObject

### Describe the solution you'd like

have an Enum Parameter on the Operation that denotes what type of `PathItemObject` the resulting operation would be.using this Enum the Document Generator should be able to add the `PathItemObject` to either the `paths` for regular endpoints or the `webhooks`

The reasoning for the use of an Enum is to make this Future compatible for other `PathItemObject` groups that future OpenApi Specs may dream up

### Additional context

_No response_