text: Title: Cancel tasks with a message where appropriate
  Body: [cancel()](https://docs.python.org/3/library/asyncio-task.html#asyncio.Task.cancel) also accepts a "msg" argument, might it be a good idea for this "message" to be added to places like https://github.com/sanic-org/sanic/blob/f7abf3db1bd4e79cd5121327359fc9021fab7ff3/sanic/server/protocols/http_protocol.py#L172 that are otherwise calling cancel() with no explanatory message?    if this is the CancelledError this user is getting, a simple message there would save everyone a lot of time.
  
  _Originally posted by @zzzeek in https://github.com/sanic-org/sanic/issues/2296#issuecomment-983881945_
  
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  Where we are able to in Py3.9, we should add a message to `cancel()`.