chore: add cosmic app list and cosmic panel buttons

applets/cosmic-app-list/src/apps_container/imp.rs

@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: MPL-2.0-only
+use gtk4::glib;
+use gtk4::subclass::prelude::*;
+use once_cell::sync::OnceCell;
+
+use crate::dock_list::DockList;
+
+#[derive(Default)]
+pub struct AppsContainer {
+    pub saved_list: OnceCell<DockList>,
+    pub active_list: OnceCell<DockList>,
+}
+
+#[glib::object_subclass]
+impl ObjectSubclass for AppsContainer {
+    // `NAME` needs to match `class` attribute of template
+    const NAME: &'static str = "AppsContainer";
+    type Type = super::AppsContainer;
+    type ParentType = gtk4::Box;
+}
+
+impl ObjectImpl for AppsContainer {}
+
+impl WidgetImpl for AppsContainer {}
+
+impl BoxImpl for AppsContainer {}