Improve mid tick chunk loading, Fix Oversleep, other improvements

Process loads outside of any canSleep check. Original intent was to
only apply those restrictions to generations but realized I had some
checks higher up the call chain.

Reworked the back off strategy to just run every 1 millisecond per world,
and to apply the per tick limit to generations only.

This guarantees that your chunk will load with at most around 1ms delay.

Additionally, fire midTick processing in a few more places, notably the
oversleep section so we can keep processing loads here too which has
a large up to 50ms window...

Speaking of oversleep, we had a bug in our implementation changes for
Timings that caused oversleep to not sleep the correct amount.

Because we now moved it into the NEXT tick instead of THIS tick, the
value of nextTick had already been increased to +50ms, resulting in
the risk of sleeping more than it should, but, more importantly, this
caused every task that was trying to NOT run during oversleep to actually
run during oversleep.

This is now fixed.

Another small tweak is to the /tps command, to no longer show the star when
TPS is right at 20.

Due to ineffeciencies in the sleep precision, TPS is commonly 20.02.
This causes the star to show up almost constantly, so now only show it if
we actually hit a real "catchup".

This commit also improves the changes to the CallbackExecutor, in that
it now is also recursion safe.

It was possible that the executor could run tasks out of desired order
if the executor task scheduled more executor tasks.

We solve this by ensuring new additions do not enter the currently iterated queue.

Each depth level will have its own queue.

Fixes #3220

Spigot-Server-Patches/Implement-extended-PaperServerListPingEvent.patch

@@ -6,7 +6,7 @@ Subject: [PATCH] Implement extended PaperServerListPingEvent
 
 diff --git a/src/main/java/com/destroystokyo/paper/network/PaperServerListPingEventImpl.java b/src/main/java/com/destroystokyo/paper/network/PaperServerListPingEventImpl.java
 new file mode 100644
-index 00000000..c1a8e295
+index 0000000000..c1a8e295b6
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/network/PaperServerListPingEventImpl.java
 @@ -0,0 +0,0 @@
@@ -43,7 +43,7 @@ index 00000000..c1a8e295
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/network/PaperStatusClient.java b/src/main/java/com/destroystokyo/paper/network/PaperStatusClient.java
 new file mode 100644
-index 00000000..a2a409e6
+index 0000000000..a2a409e635
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/network/PaperStatusClient.java
 @@ -0,0 +0,0 @@
@@ -60,7 +60,7 @@ index 00000000..a2a409e6
 +}
 diff --git a/src/main/java/com/destroystokyo/paper/network/StandardPaperServerListPingEventImpl.java b/src/main/java/com/destroystokyo/paper/network/StandardPaperServerListPingEventImpl.java
 new file mode 100644
-index 00000000..a85466bc
+index 0000000000..a85466bc7e
 --- /dev/null
 +++ b/src/main/java/com/destroystokyo/paper/network/StandardPaperServerListPingEventImpl.java
 @@ -0,0 +0,0 @@
@@ -177,7 +177,7 @@ index 00000000..a85466bc
 +
 +}
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index ae939c9b..b292e504 100644
+index 1f27939670..c502aedb8d 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
 @@ -0,0 +0,0 @@
@@ -200,7 +200,7 @@ index ae939c9b..b292e504 100644
  
              for (int k = 0; k < agameprofile.length; ++k) {
 diff --git a/src/main/java/net/minecraft/server/PacketStatusListener.java b/src/main/java/net/minecraft/server/PacketStatusListener.java
-index 658ea609..4bb21c48 100644
+index 658ea609cb..4bb21c48bd 100644
 --- a/src/main/java/net/minecraft/server/PacketStatusListener.java
 +++ b/src/main/java/net/minecraft/server/PacketStatusListener.java
 @@ -0,0 +0,0 @@ public class PacketStatusListener implements PacketStatusInListener {
@@ -223,7 +223,7 @@ index 658ea609..4bb21c48 100644
          // CraftBukkit end
      }
 diff --git a/src/main/java/net/minecraft/server/ServerPing.java b/src/main/java/net/minecraft/server/ServerPing.java
-index aa125a52..ea52e89b 100644
+index aa125a52dc..ea52e89bd9 100644
 --- a/src/main/java/net/minecraft/server/ServerPing.java
 +++ b/src/main/java/net/minecraft/server/ServerPing.java
 @@ -0,0 +0,0 @@ public class ServerPing {
@@ -248,7 +248,7 @@ index aa125a52..ea52e89b 100644
              this.c = agameprofile;
          }
 diff --git a/src/main/java/org/spigotmc/SpigotConfig.java b/src/main/java/org/spigotmc/SpigotConfig.java
-index 6d77bbc5..1cf214ea 100644
+index 6d77bbc5aa..1cf214eaca 100644
 --- a/src/main/java/org/spigotmc/SpigotConfig.java
 +++ b/src/main/java/org/spigotmc/SpigotConfig.java
 @@ -0,0 +0,0 @@ public class SpigotConfig