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/gdscript_text_document.h

@@ -46,6 +46,7 @@ protected:
 	void didChange(const Variant &p_param);
 
 	void sync_script_content(const String &p_path, const String &p_content);
+	void show_native_symbol_in_editor(const String &p_symbol_id);
 
 	Array native_member_completions;