The original API was misnamed, as the intent was to provide a manager
that decoupled state management from the service that needed to be
turned on or off. Update all the names, shortening them where
appropriate removing unncessary internal components like _service.
Also remove some API that misled developers into believing that onoff
managers are normally expected to be exposed directly to consumers.
While this is a use case, in most situations there are service or
client-specific actions that need to be coupled to transition events.
Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
8bd676ed38