This includes the "show link previews", and "enable typing
notifications" options. I also re-arranged the Security & Safety page
into more sensible groups, and in preparation for more invite options.
In my opinion, the significance of these options was still not super
clear. It wasn't obvious that the setting under Appearance will disable
them globally, and that the per-room option was discoverable.
Another change was using the term "Link preview" instead of "URL
preview", which is more common verbiage in chat applications other than
Element.
I re-arranged everything now so it makes more semantic sense, e.g. all
the message layout stuff is together in one card. I also made
bubble-only options hide themselves to reduce the amount of clutter
for compact layout users. Some small grammatical things were changed
like "Show Avatar" -> "Show Avatars".
