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/0648-Multi-Block-Change-API-Implementation.patch

@@ -1,62 +0,0 @@
-From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
-From: Brody Beckwith <brody@beckwith.dev>
-Date: Fri, 14 Jan 2022 00:41:11 -0500
-Subject: [PATCH] Multi Block Change API Implementation
-
-
-diff --git a/src/main/java/net/minecraft/network/protocol/game/ClientboundSectionBlocksUpdatePacket.java b/src/main/java/net/minecraft/network/protocol/game/ClientboundSectionBlocksUpdatePacket.java
-index 926ff9be3d9e3f5d620e4c7ccb22b9f64865ff8c..1a37654aff9a9c86c9f7af10a1cf721371f0c5ec 100644
---- a/src/main/java/net/minecraft/network/protocol/game/ClientboundSectionBlocksUpdatePacket.java
-+++ b/src/main/java/net/minecraft/network/protocol/game/ClientboundSectionBlocksUpdatePacket.java
-@@ -62,6 +62,14 @@ public class ClientboundSectionBlocksUpdatePacket implements Packet<ClientGamePa
- 
-     }
- 
-+    // Paper start - Multi Block Change API
-+    public ClientboundSectionBlocksUpdatePacket(SectionPos sectionPos, it.unimi.dsi.fastutil.shorts.Short2ObjectMap<BlockState> blockChanges) {
-+        this.sectionPos = sectionPos;
-+        this.positions = blockChanges.keySet().toShortArray();
-+        this.states = blockChanges.values().toArray(new BlockState[0]);
-+    }
-+    // Paper end - Multi Block Change API
-+
-     private void write(FriendlyByteBuf buf) {
-         buf.writeLong(this.sectionPos.asLong());
-         buf.writeVarInt(this.positions.length);
-diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
-index 85bbb04aa2f8db860780667994aba90f5b1d4d8a..ef10695d2c1c3041e5f84bdb6001c08004af9d6b 100644
---- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
-+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
-@@ -935,6 +935,32 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
-         this.getHandle().connection.send(packet);
-     }
- 
-+    // Paper start
-+    @Override
-+    public void sendMultiBlockChange(final Map<? extends io.papermc.paper.math.Position, BlockData> blockChanges) {
-+        if (this.getHandle().connection == null) return;
-+
-+        Map<SectionPos, it.unimi.dsi.fastutil.shorts.Short2ObjectMap<net.minecraft.world.level.block.state.BlockState>> sectionMap = new HashMap<>();
-+
-+        for (Map.Entry<? extends io.papermc.paper.math.Position, BlockData> entry : blockChanges.entrySet()) {
-+            BlockData blockData = entry.getValue();
-+            BlockPos blockPos = io.papermc.paper.util.MCUtil.toBlockPos(entry.getKey());
-+            SectionPos sectionPos = SectionPos.of(blockPos);
-+
-+            it.unimi.dsi.fastutil.shorts.Short2ObjectMap<net.minecraft.world.level.block.state.BlockState> sectionData = sectionMap.computeIfAbsent(sectionPos, key -> new it.unimi.dsi.fastutil.shorts.Short2ObjectArrayMap<>());
-+            sectionData.put(SectionPos.sectionRelativePos(blockPos), ((CraftBlockData) blockData).getState());
-+        }
-+
-+        for (Map.Entry<SectionPos, it.unimi.dsi.fastutil.shorts.Short2ObjectMap<net.minecraft.world.level.block.state.BlockState>> entry : sectionMap.entrySet()) {
-+            SectionPos sectionPos = entry.getKey();
-+            it.unimi.dsi.fastutil.shorts.Short2ObjectMap<net.minecraft.world.level.block.state.BlockState> blockData = entry.getValue();
-+
-+            net.minecraft.network.protocol.game.ClientboundSectionBlocksUpdatePacket packet = new net.minecraft.network.protocol.game.ClientboundSectionBlocksUpdatePacket(sectionPos, blockData);
-+            this.getHandle().connection.send(packet);
-+        }
-+    }
-+    // Paper end
-+
-     @Override
-     public void sendBlockChanges(Collection<BlockState> blocks) {
-         Preconditions.checkArgument(blocks != null, "blocks must not be null");