Add API for per-world view distances

Adapted from Spigot commit ea7e48b3e6d973551afe440a8cbc6d96a49d10fc.

By: Spottedleaf <Spottedleaf@users.noreply.github.com>

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

@@ -1536,6 +1536,13 @@ public interface World extends RegionAccessor, WorldInfo, PluginMessageRecipient
     @NotNull
     public Difficulty getDifficulty();
 
+    /**
+     * Returns the view distance used for this world.
+     *
+     * @return the view distance used for this world
+     */
+    int getViewDistance();
+
     /**
      * Gets the folder of this world on disk.
      *