Add getLibVersion and getExtVersion method for extensions and libs

src/SPC/builder/Extension.php

@@ -228,6 +228,16 @@ class Extension
         // do nothing, just throw wrong usage exception if not valid
     }
 
+    /**
+     * Get current extension version
+     *
+     * @return null|string Version string or null
+     */
+    public function getExtVersion(): ?string
+    {
+        return null;
+    }
+
     /**
      * @throws RuntimeException
      */