DDS15 — PARTITION PolicyQos should be in DataReader/DataWriter

The logic of the PARTITION Qos applies separately to each DataReader/DataWriter and the propagation on the DCPS bultin Topics also happens along with each DataReader and DataWriter.

Despite this the PARTITION Qos can only be set on the Publisher/Subscriber which impact all the DataWriters/DataReaders they contain. To overcome this we have seen many users create a separate Publisher/Subscriber per DataWriter/DataReader which unnecessarily consumes resources and couples them.

The recommendation is to allow the PARTITION Qos to be set directly on the DataWriter and DataReader. This would not impact the behavior of partition matching. Just makes it more flexible to use.

A question is whether we should still allow the Publisher/Subscriber to have a PARTITION Qos. This may be desirable to avoid braking existing code. In this case we could interpret as a 'default" unless ta DataWriter/DataReader specifies it explicitly. This would make current applications work without changes.