Update app-exit-confirm-dialog.py

[non-npc]

Resolves the following deprecation errors: window_prevent_close() dialog() window_destroy()

[ndonkoHenri]

@non-npc, thanks again for your contirbutions.

While on this, could you equally update the code you work on to use import flet as ft instead of importing each Control?

[non-npc]

@non-npc, thanks again for your contirbutions.

While on this, could you equally update the code you work on to use import flet as ft instead of importing each Control?

absolutely going forward I will do this. Thank you for making a wonderful python library.

[ndonkoHenri]

Thank you for making a wonderful python library.

@FeodorFitsner 🫡