Deprecate redundant EdmDeltaResourceObject and EdmDeltaComplexObject

[gathogojr]

Originally, EdmStructuredObject (the base class for EdmEntityObject and EdmComplexObject) did not implement IEdmChangedObject. However, four years ago, a change was introduced through [this commit](ee93798) to make EdmStructuredObject implement IEdmChangedObject. This allowed both EdmEntityObject and EdmComplexObject to represent delta payloads.

As a result, EdmDeltaResourceObject and EdmDeltaComplexObject became redundant and should have been deprecated, as noted in this TODO:
[EdmDeltaResourceObject.cs#L24](https://github.com/OData/AspNetCoreOData/blame/c60d9e0e9f68d23ee8ccd84e854ef7e430fe6edb/src/Microsoft.AspNetCore.OData/Formatter/Value/EdmDeltaResourceObject.cs#L24)

I think we should mark redundant EdmDeltaResourceObject and EdmDeltaComplexObject as obsolete and remove them in the next major release