DDS15 — DDS should require to annotate IDL to indicate which IDL types are used for dds

In a CCM/DDS4CCM based system not all IDL defined types are intended to be used with dds. At this moment there is not a standardized way to indicate that a type should be usable with DDS. If I now have a large file with a lot of types, DDS just assumes that everything should be transmittable through DDS and generates a lot of code. Just like can indicate the keys of a struct, I think DDS should define a standardized way to annotate the idl so that just some types in a file are handled by the dds tooling