Expose sleep and hibernate actions in the lock screen

kscreenlocker implements sleep and hibernate requests, but they aren't
wired anywhere in. Besides that, it can be useful to have a quick way to
suspend or hibernate computer from lockscreen.

lookandfeel/contents/lockscreen/LockScreen.qml

@@ -12,12 +12,20 @@ import "../components"
 
 Item {
     id: root
-    property bool viewVisible: false
     property bool debug: false
     property string notification
     property int interfaceVersion: org_kde_plasma_screenlocker_greeter_interfaceVersion ? org_kde_plasma_screenlocker_greeter_interfaceVersion : 0
     signal clearPassword()
 
+    // These are magical properties that kscreenlocker looks for
+    property bool viewVisible: false
+    property bool suspendToRamSupported: false
+    property bool suspendToDiskSupported: false
+
+    // These are magical signals that kscreenlocker looks for
+    signal suspendToDisk()
+    signal suspendToRam()
+
     LayoutMirroring.enabled: Qt.application.layoutDirection === Qt.RightToLeft
     LayoutMirroring.childrenInherit: true
     

lookandfeel/contents/lockscreen/LockScreenUi.qml

@@ -255,6 +255,20 @@ PlasmaCore.ColorScope {
                 }
 
                 actionItems: [
+                    ActionButton {
+                        text: i18nd("plasma_lookandfeel_org.kde.lookandfeel", "Sleep")
+                        iconSource: "system-suspend"
+                        onClicked: root.suspendToRam()
+                        visible: root.suspendToRamSupported
+                        anchors.verticalCenter: parent.top
+                    },
+                    ActionButton {
+                        text: i18nd("plasma_lookandfeel_org.kde.lookandfeel", "Hibernate")
+                        iconSource: "system-suspend-hibernate"
+                        onClicked: root.suspendToDisk()
+                        visible: root.suspendToDiskSupported
+                        anchors.verticalCenter: parent.top
+                    },
                     ActionButton {
                         text: i18nd("plasma_lookandfeel_org.kde.lookandfeel", "Switch User")
                         iconSource: "system-switch-user"