PDFViewer: Add list of recently-opened files

Author: https://github.com/AtkinsSJ
Commit: 5c76b63f79
Pull-request: https://github.com/SerenityOS/serenity/pull/18160
Reviewed-by: https://github.com/awesomekling

Userland/Applications/PDFViewer/main.cpp

@@ -27,6 +27,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto app_icon = GUI::Icon::default_icon("app-pdf-viewer"sv);
 
     Config::pledge_domain("PDFViewer");
+    app->set_config_domain(TRY("PDFViewer"_string));
 
     auto window = TRY(GUI::Window::try_create());
     window->set_title("PDF Viewer");