Add optional goto definition support for native symbols

This action will show help for target symbol in godot editor and bring the godot editor window to foreground
Improved markdown documentation for symbols.

modules/gdscript/language_server/lsp.hpp

@@ -1063,6 +1063,11 @@ struct DocumentSymbol {
 	 */
 	String documentation;
 
+	/**
+	 * Class name for the native symbols
+	 */
+	String native_class;
+
 	/**
 	 * The kind of this symbol.
 	 */