This teaches MkUrlPreview to use the activityPub element returned by Summaly. If it's present, we fetch whatever it points to, and if it's a note, we show it as if it were a normal quoted note.
A note containing such a URL ends up looking like this:
A note containing the same URL, but also actually quoting the note, only shows the real quote, not the preview-quote, because we're already filtering such duplicate URLs.
Of course if a note is a quote-renote and contains a URL to another note, we'll show both:
If we decide this is a bad idea, we could do <MkUrlPreview … :showAsQuote="!appearNote.renote"
A note containing a link to an AP object that's not a note looks normal:
