What cog is this feature request for?

Status

Describe the feature request in as much detail as possible

Add a command to clear channels from Config that have been deleted. It should be owner only and tell them the total number removed.

I have made the simple code to delete the channels:

all_cs = await self.config.all_channels()

for c in all_cs:
  chan = bot.get_channel(c)
  if chan is None:
    await self.config.channel_from_id(c).clear()

A note should also be added to the unfindable channel log about the command's existance which notes that this could be caused by a deleted channel or not having a fully chunked bot. The TODO should be removed. Both are in this file: