Refactor window handling code

Currently when we want to show/raise the window in reaction to the tray icon/notification being clicked etc we do this by emitting a signal on the controller.
This is connected to in main.qml, which does some things, then calls back to controller to do more things.

This is quite convoluted. Instead introduce a new class WindowController that is responsible for all things window, in particular showing/raising and config saving

qml/main.qml

@@ -51,7 +51,7 @@ Kirigami.ApplicationWindow {
     Timer {
         id: saveWindowGeometryTimer
         interval: 1000
-        onTriggered: Controller.saveWindowGeometry(root)
+        onTriggered: Controller.saveWindowGeometry()
     }
 
     Connections {
@@ -59,7 +59,7 @@ Kirigami.ApplicationWindow {
         enabled: false // Disable on startup to avoid writing wrong values if the window is hidden
         target: root
 
-        function onClosing() { Controller.saveWindowGeometry(root); }
+        function onClosing() { Controller.saveWindowGeometry(); }
         function onWidthChanged() { saveWindowGeometryTimer.restart(); }
         function onHeightChanged() { saveWindowGeometryTimer.restart(); }
         function onXChanged() { saveWindowGeometryTimer.restart(); }
@@ -139,13 +139,6 @@ Kirigami.ApplicationWindow {
         }
     }
 
-    function showWindow() {
-        root.show()
-        root.raise()
-        root.requestActivate()
-        Controller.raiseWindow(root)
-    }
-
     contextDrawer: RoomDrawer {
         id: contextDrawer
         modal: !root.wideScreen || !enabled
@@ -353,16 +346,6 @@ Kirigami.ApplicationWindow {
             showPassiveNotification(i18n("%1: %2", error, detail));
         }
 
-        function onShowWindow(token = null) {
-            root.showWindow()
-            if (token && KWindowSystem) {
-                KWindowSystem.setCurrentXdgActivationToken(basicNotification.xdgActivationToken)
-                KWindowSystem.activateWindow(root)
-            } else {
-                root.raise()
-            }
-        }
-
         function onUserConsentRequired(url) {
             consentSheet.url = url
             consentSheet.open()