Refactor alarm system and replace notification method

The old OpenVR overlays did not function for unknown reasons, and it was
not possible to get them to work.

With this a white overlay with ALARM ACTIVATED will be shown for 3 seconds.
It's not pretty, but it effectively communicates that an alarm has been
activated.

This fixes
https://github.com/OpenVR-Advanced-Settings/OpenVR-AdvancedSettings/issues/417

src/overlaycontroller.cpp

@@ -46,7 +46,7 @@ OverlayController::OverlayController( bool desktopMode,
     : QObject(), m_desktopMode( desktopMode ), m_noSound( noSound ),
       m_verifiedCustomTickRateMs( verifyCustomTickRate( settings::getSetting(
           settings::IntSetting::APPLICATION_customTickRateMs ) ) ),
-      m_actions()
+      m_actions(), m_alarm()
 {
     // Arbitrarily chosen Max Length of Directory path, should be sufficient for
     // Any set-up
@@ -292,6 +292,12 @@ OverlayController::OverlayController( bool desktopMode,
             QQmlEngine::setObjectOwnership( obj, QQmlEngine::CppOwnership );
             return obj;
         } );
+    qmlRegisterSingletonType<alarm_clock::VrAlarm>(
+        qmlSingletonImportName, 1, 0, "VrAlarm", []( QQmlEngine*, QJSEngine* ) {
+            QObject* obj = &( objectAddress->m_alarm );
+            QQmlEngine::setObjectOwnership( obj, QQmlEngine::CppOwnership );
+            return obj;
+        } );
 
     // Grab local version number
     QStringList verNumericalString
@@ -1185,6 +1191,8 @@ void OverlayController::mainEventLoop()
     m_audioTabController.eventLoopTick();
     m_rotationTabController.eventLoopTick( devicePoses );
 
+    m_alarm.eventLoopTick();
+
     if ( vr::VROverlay()->IsDashboardVisible() )
     {
         m_settingsTabController.dashboardLoopTick();