window: Port to AboutDialog
AboutDialog is a newer libadwaita widget that is embedded within the window, and is adaptive depending on the window size to better suit different form factors.
Before: 
After: Screencast_from_2024-06-16_20-08-00
AboutDialog is a newer libadwaita widget that is embedded within the window, and is adaptive depending on the window size to better suit different form factors.
Before:
After: Screencast_from_2024-06-16_20-08-00