Implement $ref for not schema objects as Proxy objects

[darrelmiller]

Instead of using the ReferenceObject as a placeholder and then doing a second pass to resolve the reference objects to real objects, we should create derived objects e.g. "ParameterReference" that will delegate to a target object if the property in the ParameterReference is not set. This will enable setting Summary and Description properties alongside the $ref.

See here for example https://github.com/microsoft/OpenAPI.NET/blob/dm/ProxyReference/src/Microsoft.OpenApi/Models/OpenApiSchemaReference.cs however, we will not do this on OpenAPISchema objects as they handle $ref in a native JSON Schema way. We will do this for all other types.