Add sample for badge notifications

[MartinZikmund]

What would you like to be added:

Uno Gallery sample on using badge notifications in Uno . See

• https://blog.mzikmund.com/2021/09/implementing-badge-notifications-for-uno-platform-webassembly/
• https://platform.uno/docs/articles/features/windows-ui-notifications.html
• https://github.com/unoplatform/uno/tree/master/src/Uno.UWP/UI/Notifications

Why is this needed:

Developer samples

For which Platform:

All

[AryanParashar24]

Hey @MartinZikmund i would love to work on this issue can u assign it to me😃😄