[Audio] Timeout value for "dc" setting

### What component of Red (cog, command, API) would you like to see improvements on?

Audio

### Describe the enhancement you're suggesting.

Currently it seems like the alternatives are that the bot either stays in the channel until its empty, and then disconnects after a `emptydisconnect` time, or it disconnects immediately after the queue goes empty, with the `dc` setting.

I think it would make a lot of sense if you could configure a timeout for the `dc` setting, in the form of "Wait X amount of seconds before disconnecting on empty queue". This would allow you to have the bot disconnect when its done playing, but at the same time also reduce the amount of unnecessary disconnects. I often see new songs being queued directly after the current one is done, and the bot has just 1 second ago disconnected.

### Anything else?

_No response_