Move to more modern widgets

[turtlegarden]

This pull request contains a refreshing of widgets to move to modern widgets… among other things. I got distracted. :P

An oversight of the features is as follows:

1. New AdwDialogs throughout the app:

2. Notification after moving note to trash

3. AdwBreakpoints and AdwNavigationView: see screen recording of the changing sizes here

There's still things to do here, such as figuring out the click gestures.