QoS configuration option

Hi,

Currently, Aeron does not provide a way to configure the QoS of the underlying sockets created by the media driver.

This is something users might want to have control to, depending on the workload and the underlying setup (cross-DC communication, ...)

I think this can be implemented and supported:

• At the media driver level through a configuration parameter (1-byte integer AERON_IP_TOS)
• At the channel level as a param of the uri
• Both

What do you suggest ?

I can work on an implementation on my side and then submit a PR, I just need to know what criteria my PR should meet for you guys to merge it.