Answer an rcon command after the tasks it queued have run

[lewisgibson]

Many commands that Folia dispatches to a region, the global region or an entity scheduler (time, xp query, enchant, place, weather, setblock, fill, forceload, worldborder and more) send their feedback from the task they queue, after the command itself has returned. The rcon connection was answered as soon as the command returned, so the reply was empty.

While an rcon command runs, the tasks it queues through RegionizedServer#addTask, RegionizedTaskQueue#queueTickTaskQueue, EntityScheduler#schedule (run or retired) and ServerLevel#moonrise$loadChunksAsync are tracked, and the rcon thread waits for them before it reads the response. Only the tasks the command itself queued are waited for, not the ones those tasks queue in turn, and the wait is capped at 20 seconds and happens on the rcon thread. The change is in the existing Region Threading Base patches (minecraft and paper), no new patch. It does not depend on #517.

Tested on ver/26.2.x with 53 commands sent over rcon in a row, on an unpatched build and then on this one:

• Before: 14 empty replies (time set, time add, xp query, enchant, place feature, weather, setblock, fill twice, forceload add, query and remove, worldborder get and say).
• After: only say hi is empty, and it only broadcasts to the players. time set 6000 answers Set minecraft:overworld to 6000 tick(s), xp query answers Rc has 3 experience points and forceload add 0 0 answers Marked chunk [0, 0] in minecraft:overworld to be force loaded, each within 0.1 seconds, with no errors in the log.

This was done with AI (Claude Opus 5.5 and GPT Astra, high effort). I've reviewed it and tested it myself.