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/settings/internal/settings_controller.h

@@ -546,6 +546,10 @@ private:
                          SettingCategory::Utility,
                          QtInfo{ "alarmMinute" },
                          0 },
+        IntSettingValue{ IntSetting::UTILITY_alarmSecond,
+                         SettingCategory::Utility,
+                         QtInfo{ "alarmSecond" },
+                         0 },
         IntSettingValue{ IntSetting::ROTATION_autoturnLinearTurnSpeed,
                          SettingCategory::Rotation,
                          QtInfo{ "autoturnLinearTurnSpeed" },