Make implicit rules updatable from System callers

Implicit rules don't have a ConditionProviderService nor a ConfigurationActivity, one of which is required for AutomaticZenRules. Allow the system (e.g. the user, from settings) to update them nevertheless.

Note that we still don't allow apps to update such rules, unless they are willing to add the required information.

Test: atest NotificationManagerServiceTest
Fixes: 309506066
Change-Id: Ib934cc967a59aa95643705a6f72e6443244c2335