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

build_scripts/qt/resources.pri

@@ -14,6 +14,7 @@ DISTFILES += \
     src/res/img/audio/microphone/ptt_notification.svg \
     src/res/img/battery/* \
     src/res/img/icons/* \
+    src/res/img/alarm/* \
     src/res/img/video/* \
     src/res/img/chaperone/* \
     src/res/qml/qmldir \