(FIRST 1.16.3): Update Paper to 1.16.3

This is a pretty tiny update with very little changed. Recommended to update
from 1.16.2 ASAP as 1.16.2 is now no longer supported.

Plugins should mostly remain working as the NMS revision did not change.

Spigot-Server-Patches/Add-tick-times-API-and-mspt-command.patch

@@ -116,8 +116,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
          this.methodProfiler.exit();
          org.spigotmc.WatchdogThread.tick(); // Spigot
 @@ -0,0 +0,0 @@ public abstract class MinecraftServer extends IAsyncTaskHandlerReentrant<TickTas
-     public IRegistryCustom aX() {
-         return this.f;
+     public IRegistryCustom getCustomRegistry() {
+         return this.customRegistry;
      }
 +
 +    // Paper start