Handling app termination and reworked dialog messages.

[bkaankose]

This PR implements killing the server process when the app is terminated and re-works how the dialogs are presented.

• App will show a message on close to the users if their backgrounding behavior is set to 'Terminate' (which will kill the server) and if they did not enable Wino launch for startup. These messages can be marked as 'Don't show again', allowing users to acknowledge this behavior and continue.
• All dialogs will have an icon from now on.

Also fixed some low hanging fruit bugs from the App Center.

• Fixed an issue where updating badge notification causes a crash if the device does not support badge notifications.
• Fixed an issue with read but downloaded messages creating notification.
• Fixed an issue where clicking another draft from the draft list is crashing WebView2.