Grouped all 'New XXX...' operations in a 'New...' sub menu

This will reduce the height of the rather large context menu and gives us the possibility to add more 'New XXX...' operations in the future without cluttering the menu and thus making it taller.

editor/filesystem_dock.cpp

@@ -2590,11 +2590,18 @@ void FileSystemDock::_file_and_folders_fill_popup(PopupMenu *p_popup, Vector<Str
 	if (p_paths.size() == 1) {
 		p_popup->add_separator();
 		if (p_display_path_dependent_options) {
-			p_popup->add_icon_item(get_theme_icon(SNAME("Folder"), SNAME("EditorIcons")), TTR("New Folder..."), FILE_NEW_FOLDER);
-			p_popup->add_icon_item(get_theme_icon(SNAME("PackedScene"), SNAME("EditorIcons")), TTR("New Scene..."), FILE_NEW_SCENE);
-			p_popup->add_icon_item(get_theme_icon(SNAME("Script"), SNAME("EditorIcons")), TTR("New Script..."), FILE_NEW_SCRIPT);
-			p_popup->add_icon_item(get_theme_icon(SNAME("Object"), SNAME("EditorIcons")), TTR("New Resource..."), FILE_NEW_RESOURCE);
-			p_popup->add_icon_item(get_theme_icon(SNAME("TextFile"), SNAME("EditorIcons")), TTR("New TextFile..."), FILE_NEW_TEXTFILE);
+			PopupMenu *new_menu = memnew(PopupMenu);
+			new_menu->set_name("New");
+			new_menu->connect("id_pressed", callable_mp(this, &FileSystemDock::_tree_rmb_option));
+
+			p_popup->add_child(new_menu);
+			p_popup->add_submenu_item(TTR("New"), "New");
+
+			new_menu->add_icon_item(get_theme_icon(SNAME("Folder"), SNAME("EditorIcons")), TTR("Folder..."), FILE_NEW_FOLDER);
+			new_menu->add_icon_item(get_theme_icon(SNAME("PackedScene"), SNAME("EditorIcons")), TTR("Scene..."), FILE_NEW_SCENE);
+			new_menu->add_icon_item(get_theme_icon(SNAME("Script"), SNAME("EditorIcons")), TTR("Script..."), FILE_NEW_SCRIPT);
+			new_menu->add_icon_item(get_theme_icon(SNAME("Object"), SNAME("EditorIcons")), TTR("Resource..."), FILE_NEW_RESOURCE);
+			new_menu->add_icon_item(get_theme_icon(SNAME("TextFile"), SNAME("EditorIcons")), TTR("TextFile..."), FILE_NEW_TEXTFILE);
 			p_popup->add_separator();
 		}