Personas feature (to support plural systems and roleplay) (WIP)

I would also like to emphasise that subprofile data should be private if the user wishes, and a full subprofile list should not be accessible (through UI, API, or otherwise) if the user does not want it.

@j0lol This can be accomplished via OAuth2 scopes, part of my point number 7. I'm also suggesting that streamer mode could also aid in hiding subprofile information, though some users may want to keep some subprofiles public at all times. This is also part of what I'm worried about: the subprofile feature becoming too heavy.

We've discussed the name quite a lot, and we chose not to call it "subprofiles" because it could be confused with community-specific profiles that way. Personas is kinda the next-best fit.

Thank you for the input! Subprofiles was what I used initially and is still definitely my 2nd choice, I'm flexible on the naming, but it was causing confusion with server profiles and for a general audience was a little too technical and less clear. Can have a broader discussion about revisiting the naming later. Making the picker responsive as they type a proxy tag is a good idea (much like how emojis work currently) but it risks being annoying since unlike with emojis, there is no single trigger character for tag prefixes. Like if I start a sentence with "C" should it just pop up all my personas with prefix tags starting with C even if I'm typing "Call me" or "Come on"? Maybe you'd have to hit TAB to show options. Or maybe it should be a user setting. I'm really not sure. In my most recent update I defined an unlisted/public/private system for personas where unlisted is the default (meaning details like bio of a persona are only available to those who see your messages and share a server/guild or are friends). Public means it shows up in the public persona listing for their account, private means it doesn't appear in the listing and also cannot be queried (they only see the bare minimum name and avatar in the snapshot data attached to messages). I'm open to revisiting this design, it's preliminary.

Check out https://utter.y2k.diy/ and you'll see what I mean by the responsive picker.

I see what you mean now about the icon showing up based on what tag you're using in current message. Right now in current design the selector is showing active (default untagged) persona but I like the idea of it switching based on who the current message will be sent as, just as an extra visual indicator/warning. That's a good idea and I'll go ahead and do it. Edit: It is done, it's very cool! I was thinking of also having some kind of prefix character like & or something to search personas and then inject the prefix/suffix without having to click on the selector button, but that's a separate thing for later.