Backport Emoji changes to share the same (and newer) emojibase data

So... My initial itch was to just import Unicode 13 data in gtk3 to support newer emojis.

But, considering that now the previously used source isn't updated (even though there are others, but...) and that nice fixes have landed on gtk4, I thought that it was just better to backport the uncontroversial (hopefully) changes to gtk3 making both toolkits to share the same data (so that next updates can be just matter of copy/paste - or regenerate from the same trusted source).

The only "break" caused by this would be loosing the history of "Last used emoji"'s list, HOWEVER, I've hacked a workaround to prevent this to happen, by basically using a different data structure for the recent emojis (that is the same as before) and the one of the db.

This is probably not really needed and I'm happy to remove the commit in case (I'm still wondering why we've to save so much data in the recent-emoji key, given that searching could probably be skipped for them).

I've also included the metadata update as per !3520 (merged)