Remove duplicate views: Show notices

[mmtr]

See pekYwv-4QW-p2

We need to show a notice when the WP Admin view is enforced for users participating in the remove duplicate views experiment.

We need to show them only to users currently using the default admin interface, and in every screen that is enforced. Each notice can be permanently dismissed.

[github-actions]

This issue could use some more labels, to help prioritize and categorize our work. Could you please add at least a [Type], a [Feature], and a [Pri] label?

[matt-west]

@mmtr Can you please update the modals based on these new designs. This requires updates to the illustrations and copy.

See the discussion here for more context: pdtkmj-3dx-p2

[github-actions]

This issue could use some more labels, to help prioritize and categorize our work. Could you please add at least a [Type], a [Feature], and a [Pri] label?

[mmtr]

@matt-west I just created a follow-up issue (#98088), so I'll track the work there.