[UX] Idea: replace the various options for registering/canceling user accounts with a set of permissions

In #3816, we are working towards reducing confusion by clarifying terminology used in the labels of radios/checkboxes (i.e. "who is considered an administrator?"). I took a look at the help text that we are adding and it occurred to me that: - things already seem to revolve around existing permissions ("Administer user accounts", "Select method of canceling account") - the "who can register accounts?" setting already sounds like a permission - as it is, we need extensive help text in order to explain how things work - perhaps things would be clearer if we had separate permissions for each action(?)

So I would like to explore the idea of switching to injecting a permission matrix in that form instead (#3332), and introducing new permissions to handle these things.

mockup upcoming...