implement `main_channel` in Voice

[50thomatoes50]

this is to calculate actual time in special squad. for now implementation doesn't check and use first VC joined in Patrol

Many issues:

• automatic guess may not always work, we need event host/dispatch to be able to correct the info?
• would be better to use a job every hour when there is low population, because doing it at the end of a patrol would make the bot lag or overload the server with requests.

maybe we don't even bother and just use a crude implementation and don't mind the few edge cases

[50thomatoes50]

doesn't need to be automated can be manual by event host