Add Lifecycle Event system

This event system is separate from Bukkit's event system and is
meant for managing resources across reloads and from points in the
PluginBootstrap.

paper-server/src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -1062,6 +1062,11 @@ public final class CraftServer implements Server {
 
     @Override
     public void reload() {
+        // Paper start - lifecycle events
+        if (io.papermc.paper.plugin.lifecycle.event.LifecycleEventRunner.INSTANCE.blocksPluginReloading()) {
+            throw new IllegalStateException("A lifecycle event handler has been registered which makes reloading plugins not possible");
+        }
+        // Paper end - lifecycle events
         org.spigotmc.WatchdogThread.hasStarted = false; // Paper - Disable watchdog early timeout on reload
         this.reloadCount++;
         this.configuration = YamlConfiguration.loadConfiguration(this.getConfigFile());

paper-server/src/main/java/org/bukkit/craftbukkit/util/CraftMagicNumbers.java

@@ -649,6 +649,13 @@ public final class CraftMagicNumbers implements UnsafeValues {
     }
     // Paper end - spawn egg color visibility
 
+    // Paper start - lifecycle event API
+    @Override
+    public io.papermc.paper.plugin.lifecycle.event.LifecycleEventManager<org.bukkit.plugin.Plugin> createPluginLifecycleEventManager(final org.bukkit.plugin.java.JavaPlugin plugin, final java.util.function.BooleanSupplier registrationCheck) {
+        return new io.papermc.paper.plugin.lifecycle.event.PaperLifecycleEventManager<>(plugin, registrationCheck);
+    }
+    // Paper end - lifecycle event API
+
     /**
      * This helper class represents the different NBT Tags.
      * <p>