Summary:
Diff removes view-as pill in the document breadcrumbs and add new view-as banner.
Note: Banners are still missing mechanism to handle several banners. As of now both doc-usage and view-as banners could show up at the same time.
Test Plan: Refactored existing test.
Reviewers: jarek
Reviewed By: jarek
Subscribers: jarek
Differential Revision: https://phab.getgrist.com/D3732
