Unify StreamQos messages

[xtor]

After the merge of listener support, we should refactor the protobuf stream request messages.

More details to come in this ticket once the PR is merged. The key ideas are:

• We can reuse almost all the info for talker and listener in the same request, with a field to discriminate the type
• Most fields can be used without further change. But for txmin,txmax, we may rename as e.g. offsetmin offsetmax, so they would fit on Rx as well.

Additional changes:

• Harmonize naming of Configuration classes. E.g. StreamConfiguration and ListenerConfiguration to e.g. TalkerStreamConfiguration and ListenerStreamConfiguration.