Remove wall-time / unused skip tick protection (#11412)

Spigot still maintains some partial implementation of "tick skipping", a
practice in which the MinecraftServer.currentTick field is updated not
by an increment of one per actual tick, but instead set to
System.currentTimeMillis() / 50. This behaviour means that the tracked
tick may "skip" a tick value in case a previous tick took more than the
expected 50ms.

To compensate for this in important paths, spigot/craftbukkit
implements "wall-time". Instead of incrementing/decrementing ticks on
block entities/entities by one for each call to their tick() method,
they instead increment/decrement important values, like
an ItemEntity's age or pickupDelay, by the difference of
`currentTick - lastTick`, where `lastTick` is the value of
`currentTick` during the last tick() call.

These "fixes" however do not play nicely with minecraft's simulation
distance as entities/block entities implementing the above behaviour
would "catch up" their values when moving from a non-ticking chunk to a
ticking one as their `lastTick` value remains stuck on the last tick in
a ticking chunk and hence lead to a large "catch up" once ticked again.

Paper completely removes the "tick skipping" behaviour (See patch
"Further-improve-server-tick-loop"), making the above precautions
completely unnecessary, which also rids paper of the previous described
incompatibility with non-ticking chunks.

patches/server/0893-Add-player-idle-duration-API.patch

@@ -0,0 +1,30 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: booky10 <boooky10@gmail.com>
+Date: Sat, 14 Oct 2023 03:11:11 +0200
+Subject: [PATCH] Add player idle duration API
+
+Implements API for getting and resetting a player's idle duration.
+
+diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+index a1b870fb3d1fd5d209474c47bf523d0d5d58ce39..1d79bacbfb24442573245550263141ad56332971 100644
+--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
++++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+@@ -3419,6 +3419,18 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
+     }
+     // Paper end
+ 
++    // Paper start
++    @Override
++    public Duration getIdleDuration() {
++        return Duration.ofMillis(net.minecraft.Util.getMillis() - this.getHandle().getLastActionTime());
++    }
++
++    @Override
++    public void resetIdleDuration() {
++        this.getHandle().resetLastActionTime();
++    }
++    // Paper end
++
+     public Player.Spigot spigot()
+     {
+         return this.spigot;