As requested in #46676 and many other similar issues, I think it would be super useful to be able to mute notifications as well as enable and disable notifications for specific extensions.

Exploration

Here's how this could look:

• Expose a menu on the notification list header to manage notifications for all or specific notifications
• Expose a mute action on the notification list header that toggles the mute state. This could also be extended to mute for a specific duration (e.g. "Mute for 1 hour")

I'm not happy with the icon choice for muting yet—let me know if there are any ideas here. I think the "bell with slash" icon is clear enough as a way to represent "muted" but I don't like using the regular bell icon for the mute action since it duplicates the main notification icon.