[Voice] Bots hinting available voice regions

[PapiOphidian]

The current behavior for both users and bots is that when they join a voice channel, the region they are connecting to will either be the region the first connected user is in or, in some cases as I have been told, an automatically adjusted region which is somewhere in between all connected users. This works great for users, but bots are a different story as they are not constrained to 1 machine or region.

I believe it would be beneficial for users if bots could hint to the api/gateway what regions they have access to so that the api/gateway doesn't have to use just their geo IP location to guess nearby regions and instead can pull from that list and the bot can connect with the closest audio node based on the region from VOICE_SERVER_UPDATE's endpoint member.

I am not currently aware if VOICE_SERVER_UPDATE is fired when the voice region is automatically adjusted internally, but I would imagine it is. Anyways, I believe this would work even if it were to be adjusted so that the bot can switch audio nodes to the region closest to the adjusted region when VOICE_SERVER_UPDATE is fired again so that there's less distance to cover.