Rework async chunk api implementation

Firstly, the old methods all routed to the CompletableFuture method.
However, the CF method could not guarantee that if the caller
was off-main that the future would be "completed" on-main. Since
the callback methods used the CF one, this meant that the callback
methods did not guarantee that the callbacks were to be called on
the main thread.

Now, all methods route to getChunkAtAsync(x, z, gen, urgent, cb)
so that the methods with the callback are guaranteed to invoke
the callback on the main thread. The CF behavior remains unchanged;
it may still appear to complete on main if invoked off-main.

Secondly, remove the scheduleOnMain invocation in the async
chunk completion. This unnecessarily delays the callback
by 1 tick.

Thirdly, add getChunksAtAsync(minX, minZ, maxX, maxZ, ...) which
will load chunks within an area. This method is provided as a helper
as keeping all chunks loaded within an area can be complicated to
implement for plugins (due to the lacking ticket API), and is
already implemented internally anyways.

Fourthly, remove the ticket addition that occured with getChunkAt
and getChunkAtAsync. The ticket addition may delay the unloading
of the chunk unnecessarily. It also fixes a very rare timing bug
where the future/callback would be completed after the chunk
unloads.

patches/server/0925-Add-BlockBreakProgressUpdateEvent.patch

@@ -1,28 +0,0 @@
-From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
-From: Badbird5907 <50347938+Badbird5907@users.noreply.github.com>
-Date: Mon, 4 Mar 2024 22:18:28 -0500
-Subject: [PATCH] Add BlockBreakProgressUpdateEvent
-
-
-diff --git a/src/main/java/net/minecraft/server/level/ServerLevel.java b/src/main/java/net/minecraft/server/level/ServerLevel.java
-index 7a985c30a973efacf3e8b70e7163c550d86b0870..ea1281c9a3b83b17de64d583e029db9bacabcd88 100644
---- a/src/main/java/net/minecraft/server/level/ServerLevel.java
-+++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
-@@ -1285,6 +1285,17 @@ public class ServerLevel extends Level implements ServerEntityGetter, WorldGenLe
-         if (entity instanceof Player) entityhuman = (Player) entity;
-         // CraftBukkit end
- 
-+        // Paper start - Add BlockBreakProgressUpdateEvent
-+        // If a plugin is using this method to send destroy packets for a client-side only entity id, no block progress occurred on the server.
-+        // Hence, do not call the event.
-+        if (entity != null) {
-+            float progressFloat = Mth.clamp(progress, 0, 10) / 10.0f;
-+            org.bukkit.craftbukkit.block.CraftBlock bukkitBlock = org.bukkit.craftbukkit.block.CraftBlock.at(this, pos);
-+            new io.papermc.paper.event.block.BlockBreakProgressUpdateEvent(bukkitBlock, progressFloat, entity.getBukkitEntity())
-+                .callEvent();
-+        }
-+        // Paper end - Add BlockBreakProgressUpdateEvent
-+
-         while (iterator.hasNext()) {
-             ServerPlayer entityplayer = (ServerPlayer) iterator.next();
-