Update the Settings pages for Notifications

[daniellekirkwood]

In line with element-meta 887 this issue is the meta issue for updating the visuals and hierarchy on the notifications settings pages in Element.

We'll design the cross-platform changes for these pages, then implement them as time allows...

• Web & Desktop notifications settings page via the top-left profile mentions
• Web & Desktop room level notification settings and their access points (top room name and right-panel)
• Web & Desktop contextual actions
• Mobile > User Settings > Notifications >
• Room > Settings > Notifications >
• Context menu from the room list > Notifications >

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			https://user-images.githubusercontent.com/89144281/209364366-03fba8f1-9d1b-4ca0-8440-3aa43b473c63.MP4

[daniellekirkwood]

We need design principles for these pages, along with designs that can be implemented by the team.