Add a "comments-mode" to the client

[seanh]

Problem

Some publishers (for example bioRxiv) just want a comments feature for their website, not annotations.

Solution

Add an optional "comments mode" setting to the embedded client that hides all annotation-related features, leaves only page notes, and refers to page notes as "comments". In addition, when in comments mode the design and layout of the client UI will be tweaked slightly to look better as a commenting-only system.

Here's how we want the client's UI to appear when in comments mode (Figma link):

Done when

We'll use our bioTome demo site to test and demo this new mode: https://biotome.hypothes.is/

• The client's UI on https://biotome.hypothes.is/ looks like the mockup above
• Selecting text on https://biotome.hypothes.is/ does not open the Annotate/Highlight popover
• The Annotations | Page Notes | Orphans tabs at the sidebar are not visible
• Page notes are always shown in the sidebar
• Page notes are sorted newest first by default (this differs from the default behaviour when not in comments-mode: page notes are sorted oldest-first by default)
• There's a button in the sidebar for creating a new comment
  • The + New note button label has been changed to + Add comment
• "Annotations" has been removed from the placeholder text in the search field (currently Search annotations...) (Done: Replace "Search annotations..." with just "Search..." #7066)
• The text There are no page notes in this group has been changed to There are no comments on this page. Create one by clicking the + button.
• The Help/Getting started dialog has been removed or changed to no longer mention annotations.
• Share this annotation in the share link popover has been changed to Share this comment
• Only you may view this annotation in the share link popover has been changed to Only you may view this comment
• Any other mentions of "annotation" or "page note" anywhere in the UI have been hidden or replaced with "comment" as appropriate