Feature Request

Add NoopCompleter to always return a nil []prompt.Suggest.

func NoopCompleter(d prompt.Document) []prompt.Suggest {
	return nil
}

Somethings I just want to use this lib to receive a simple input, no suggestions at all, but every time I have to write a noop completer to achieve this.

So I wonder whether we can add a NoopCompleter to do this.