First pass at the new video tile designs

Here, I've begun updating the styles of video tiles to match the new designs. Not yet updated: the local volume option is supposed to go inside an overflow menu now, but I haven't gotten to that yet.

To make the outlines on hovered / speaking tiles show up properly, I have to remove the usePageFocusStyle hack, which was preventing CSS outlines from being used for anything other than focus rings. I honestly can't tell what problem it was solving in the first place: focus rings still appear to behave as expected throughout the application.

public/locales/en-GB/app.json

@@ -116,6 +116,7 @@
   "Walkie-talkie call": "Walkie-talkie call",
   "Walkie-talkie call name": "Walkie-talkie call name",
   "Yes, join call": "Yes, join call",
+  "You": "You",
   "You were disconnected from the call": "You were disconnected from the call",
   "Your feedback": "Your feedback",
   "Your recent calls": "Your recent calls"