Add notifcation settings screen

[itsmeichigo]

There are feature requests for disabling push notifications for product reviews while keeping those for orders.

This should be handled on a new screen for notification settings.

• HACK Week: New screen for notification settings #15373
• HACK Week: Update notification settings to reflect notification permission #15378
• HACK Week: Show site list on notification settings screen for configurations #15383
• HACK Week: Integrate loading notification settings #15385
• HACK Week: Load and update site settings #15386

[dangermattic]

🚫 Please add a type label (e.g. type: enhancement) and a feature label (e.g. feature: stats) to this issue.