Refactor the SMF provider to implement enableable semantics

The SMF provider did not properly implement enableable semantics. For example, enabling a service also starts it, while disabling a service also stops it. That means if we do enable => true, ensure => stop The final state of the service is undefined – it will either be stopped (and disabled from starting up at boot) or running (and enabled to start at boot). We want it to be stopped, but enabled to start up again upon a reboot. After this commit the enable and ensure are independent operations where enable handles whether the service starts or stops at boot time, while ensure handles whether the service starts or stops in the current running instance