Is your feature request related to a problem? Please describe.

reopen AArnott#22.

The main purpose is to serialize/deserialize nonpublic members with marked DataMemberAttribute, but those without DataMemberAttribute must be excluded, even public members.

Additional context

If necessary, I can assist in establishing a PR.

There are currently two options in mind.

1. Change the behavior of the existing DynamicObjectResolver.
2. Add a DataContractSerializerCompatibilityResolver to handle it.

Which one is better?
Any suggestions?