/back imcompat with journeymap

[arnokeesman]

in hopes of not losing this in discord
a user reported /back not working from time to time for some opped player (probably)
this was fixed when JM was removed from the server
I asked the dev, here's wat I learned:

if journeymap is on the server, it does not use the command. If journeymap is not on the server, 1.21+ uses the execute command. older versions use the tp command.
it uses the vanilla entity teleport logic

(where "JM on the server" means on both the server and client naturally, with the user using the map to teleport)

Do we want to move the /back mixin from the tp command to the PlayerEntity logic, or just leave this as is?

[John-Paul-R]

That's a good question. This is one of those things where iirc I intentionally chose to hook into /tp to avoid /back granting utility in unintended scenarios.

I definitely see the use of being more aggressive with tracking points for /back, so... I might make it a config option?