SPIGOT-6729: Add Chunk.isEntitiesLoaded()

By: Brokkonaut <hannos17@gmx.de>

paper-api/src/main/java/org/bukkit/Chunk.java

@@ -69,6 +69,13 @@ public interface Chunk extends PersistentDataHolder {
     @NotNull
     ChunkSnapshot getChunkSnapshot(boolean includeMaxblocky, boolean includeBiome, boolean includeBiomeTempRain);
 
+    /**
+     * Checks if entities in this chunk are loaded.
+     *
+     * @return True if entities are loaded.
+     */
+    boolean isEntitiesLoaded();
+
     /**
      * Get a list of all entities in the chunk.
      * This will force load any entities, which are not loaded.