Reflect nicknames on scoreboards

[HoldYourWaffle]

It'd be great if nicknames could be reflected on scoreboards.

I might have some time to take a shot at this in a couple days, though I could see this being challenging to implement due to MC-50247...

[Patbox]

Try using the /scoreboard objectives modify OBJECTIVE displayautoupdate true. It should make it update once score changes

[HoldYourWaffle]

Huh, that's an interesting mechanic. It seems to work, though with some downsides:

1. All (visible) scoreboards need to be manually configured for this.
2. Nickname changes are only propagated when a score changes.
3. This replaces the vanilla "set specific display name to override player name" mechanic.
4. Nicknames end up persisted in scoreboards.dat.

I wonder if this could be accomplished by hijacking something like ScoreboardScoreUpdateS2CPacket. That'd make it purely a visual change for clients, which I'd expect to be safer. Some initial poking seems promising, though there's a weird interaction with team coloring that I haven't figured out yet.

I also looked into PlayerEntity.getNameForScoreboard, but those values are persisted in even more troublesome ways and would almost certainly break compatibility with something like Score Migrator.

[HoldYourWaffle]

It seems that team colors don't update correctly with this workaround either, though I haven't properly investigated this yet.