ISerializable cleanup (#11873)

ISerializable cleanup (#11873)

Changes to throw PlatformNotSupportedException from ISerializable.GetObjectData and serialization constructors on non-Serializable types. Also removes private serialization constructors and some unneeded code that was used to support serializing non-serializable types. A few tests testing GetObjectData implementations are also removed. For Exception types, we call base instead of throwing from GetObjectData to be consistent with the many Exceptions that don't override GetObjectData