refactor(systemd): Depend on calling code to populate UnitState.MachineState
test(systemd): Use random unit name
test(systemd): Assert unit state after loading
test(systemd): Start and stop units, asserting state in between
refactor(systemd): Separate event code from SystemdManager
refactor(engine): Move event components out of engine
refactor(agent): Call Initialize before Run
refactor(*): Move event init to server pkg