DEV: Render glimmer notification items for user notification list (#24802)

This removes the widget notifications list and renders the glimmer user menu notification items instead.

spec/system/user_page/user_notifications_spec.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+describe "User notifications", type: :system do
+  fab!(:user)
+  let(:user_notifications_page) { PageObjects::Pages::UserNotifications.new }
+
+  fab!(:read_notification) { Fabricate(:notification, user: user, read: true) }
+  fab!(:unread_notification) { Fabricate(:notification, user: user, read: false) }
+
+  before { sign_in(user) }
+
+  describe "filtering" do
+    it "saves custom picture and system assigned pictures" do
+      user_notifications_page.visit(user)
+      user_notifications_page.filter_dropdown
+      expect(user_notifications_page).to have_selected_filter_value("all")
+      expect(user_notifications_page).to have_notification(read_notification)
+      expect(user_notifications_page).to have_notification(unread_notification)
+
+      user_notifications_page.set_filter_value("read")
+
+      expect(user_notifications_page).to have_notification(read_notification)
+      expect(user_notifications_page).to have_no_notification(unread_notification)
+
+      user_notifications_page.set_filter_value("unread")
+
+      expect(user_notifications_page).to have_no_notification(read_notification)
+      expect(user_notifications_page).to have_notification(unread_notification)
+    end
+  end
+end