Add bPermissions migration

common/src/main/java/me/lucko/luckperms/LuckPermsPlugin.java

@@ -136,6 +136,13 @@ public interface LuckPermsPlugin {
      */
     Object getService(Class clazz);
 
+    /**
+     * Used as a backup for migration
+     * @param playerName the players name
+     * @return a uuid if found, or null if not
+     */
+    UUID getUUID(String playerName);
+
     /**
      * Checks if a plugin is loaded on the platform
      * @param name the name of the plugin