activate
Activates the feature on the connected device.
During the call, feature emits LoadingState.InProgress. On success, feature emits the refetched underlying feature instance with LoadingState.Done.
If the feature is already active this call is a no-op at the device level and still returns ProcessingFeatureActivationResult.Success — the refetch still runs so the observable emits the latest device state.
Return
ProcessingFeatureActivationResult.Success when the device acknowledges the change (or it was already active) and the refetch succeeded; ProcessingFeatureActivationResult.Failure otherwise.