Move ToSerial and ToEnum to SerializationProviders from EnumProvider class

[nisha-bhatia]

Currently ToSerial and ToEnum are on the EnumProvider class. They do not belong here - as they are currently used for serialization. If we move To{Type.Name} to SerializationProviders we can ensure that the method will always have an implementation (in case the enum is overriden and doesn't have a ToName method).

Addresses this comment: #3621 (comment)

[ArcturusZhang]

So I think we have a contradiction with the comment here if make the suggested change here: #3642 (comment)