Added an icon to show the visibility of a status (public, unlisted,
private, or direct). This goes next to the up arrow indicating
a reply, so this area can be used for other symbols regarding the
status' properties.
Created a new page to display account info. Just shows a link
to the user's home instance and their bio, plus indicators showing
whether the user is a bot and whether their account is locked.
Implemented a new page that shows a status context, though I'm
calling it a "thread" in the UI because I think that makes more
sense for users. Also moved the action element from the notification
into the event info component itself because I also want to use it
to indicate when a status is a reply.