Lets AI and Borgs control radio behavior for auto announcements.

The AI and cyborgs can now control if they speak on the radio and the
channel used when stating laws or (AI only) announcing new player
arrivals.
- By default, the AI will state laws and announce new players on its internal radio using the Common channel, which mimics the previous functionality of the AI announcing its laws and new players on its intercom.
- Cyborgs do not normally state their laws on radio, so they, by default, speak locally when stating laws until configured otherwise.
- Cyborgs must be in <i>subspace transmission mode</i> in order to view and set any department channels installed on their radio.
- If the AI is a Traitor, it will be able to set the Syndicate channel for auto-announcements. The same goes for cyborgs which have had a syndicate radio key installed (including Syndiborgs).

fixes https://github.com/tgstation/-tg-station/issues/5860

This is technically both a fix and a feature, tag accordingly if you wish. 
Yes, but it is long and annoying. I did that to make it look neater since it is used in several places.