QText should support emoji

(User Story, Investigate , Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )
QText
Summary: This needs to be fleshed out, but at this point emoji are a reality that we should incorporate. At the very least, they are essential in conversations, and we might as well just build them into QText more generally.
It isn't strictly obvious which dialect of emoji we support. I'm mildly inclined towards following Slack's lead (using a syntax like :+1:), if that is open for use, but there are many other options.
Preferably, it should be possible to define Space-specific emoji. People enjoy doing that, and there's no reason not to allow it.