Add method to get ungenerated chunk from long key (#9254)

Also added a missing deprecation for a location block key method

patches/api/isChunkGenerated-API.patch

@@ -38,10 +38,10 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 --- a/src/main/java/org/bukkit/World.java
 +++ b/src/main/java/org/bukkit/World.java
 @@ -0,0 +0,0 @@ public interface World extends RegionAccessor, WorldInfo, PluginMessageRecipient
-     public default Chunk getChunkAt(long chunkKey) {
-         return getChunkAt((int) chunkKey, (int) (chunkKey >> 32));
      }
-+
+     // Paper end - chunk long key API
+ 
++    // Paper start - isChunkGenerated API
 +    /**
 +     * Checks if a {@link Chunk} has been generated at the specified chunk key,
 +     * which is the X and Z packed into a long.
@@ -49,9 +49,11 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +     * @param chunkKey The Chunk Key to look up the chunk by
 +     * @return true if the chunk has been generated, otherwise false
 +     */
-+    public default boolean isChunkGenerated(long chunkKey) {
++    default boolean isChunkGenerated(long chunkKey) {
 +        return isChunkGenerated((int) chunkKey, (int) (chunkKey >> 32));
 +    }
-     // Paper end
- 
++    // Paper end - isChunkGenerated API
++
      /**
+      * Checks if the specified {@link Chunk} is loaded
+      *