Goal: Improve macOS (darwin) launchctl commands

[n8felton]

The goal of this issue is to replace some of the older, legacy, launchctl commands with more modern ones. See fleetdm/fleet#3995 for examples.

The most notable change to deal with is replacing the output of launchctl list with launchctl print

service/service_darwin.go

Line 217 in 3596dfa

exitCode, out, err := runWithOutput("launchctl", "list", s.Name)

To make things more fun and interesting, man launchctl specifically calls out

IMPORTANT: This output is NOT API in any sense at all. Do NOT rely
on the structure or information emitted for ANY reason. It may
change from release to release without warning.

To make things even more fun, Apple is is deprecating the current form of LaunchAgents and LaunchDaemons, so we'll need to keep an eye on that...

https://developer.apple.com/documentation/servicemanagement/updating_helper_executables_from_earlier_versions_of_macos

CC: #322

[prochac]

Is replacement of something that works, by something that can break, even a step forward?