Swift template - handle models and request with the same name

[yonaskolb]

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At the moment the Swift compiler can complain if 2 files have the same filename, which can happen if a model name and operationId are the same, for example a model called Purchase.swift and a request called Purchase.swift

[yonaskolb]

Renaming models from https://github.com/yonaskolb/SwagGen/issues/90 can resolve this