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>
k_poll() for a signal is often desired for notification of completion
of asynchronous operations, but there are APIs where it may be
necessary to invoke "asynchronous" operations from contexts where
sleep is disallowed, or before the kernel has been initialized.
Extract the general notification solution from the on-off service into
a utility that can be used for other APIs.
Also move documentation out to a resource management section.
Signed-off-by: Peter Bigot <peter.bigot@nordicsemi.no>
