Firebase Analytics -- frontend

[Levi-Lesches]

Most of the analytics can be handled in the models layer, but some need to be inserted directly in the UI. We need to call the following functions from Services.instance.analytics:

• onAppOpen: in main.dart
• onLogin: in LoginState.signIn
• setBrightness: in BrightnessChanger.setBrightness
• page tracker: Check out the docs for instructions