sACN CID is not unique

[calebwest-SS]

Environment

• OS: Windows, Linux
• Version 1.9.17

Describe the bug
In sACN, there is a "CID" value that is sent with each packet. In Chataigne, that is sent as a full string of zeros. This means that if two instances of chataigne exist on the same sACN network, the gateways have no way to differentiate, and will randomly jump back and forth (or strobe back and forth).

To Reproduce
Steps to reproduce the behavior:

1. Turn on DMX output from one sACN instance
2. On another device, turn on DMX output for the same universe

Expected behavior
There should be differences in the CID sent from each device. Generally, this is set by a manufacturer to be different for every single device.

Additional context
I am going to look into a fix for this, as a part of my general look into the way Chataigne is handling sACN DMX. I think this should be user set, unless I can come up with an elegant way to generate these on a per-module basis.