applet: Introduce StackView for contents
Enables us to push different subpages, such as QR code scanner or viewer, similar to how Klipper does it.
Split that out from !178
and put the QR code share thing into it while at it.
Enables us to push different subpages, such as QR code scanner or viewer, similar to how Klipper does it.
Split that out from !178
and put the QR code share thing into it while at it.