FEATURE: Add bulk destroy to admin users list (#29744)

This commit introduces a new feature that allows staff to bulk select and delete users directly from the users list at `/admin/users/list`. The main use-case for this feature is make deleting spammers easier when a site is under a large spam attack.

Internal topic: t/140321.

spec/system/page_objects/components/d_menu.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+module PageObjects
+  module Components
+    class DMenu < PageObjects::Components::Base
+      attr_reader :component
+
+      def initialize(input)
+        if input.is_a?(Capybara::Node::Element)
+          @component = input
+        else
+          @component = find(input)
+        end
+      end
+
+      def expand
+        raise "DMenu is already expanded" if is_expanded?
+        component.click
+      end
+
+      def collapse
+        raise "DMenu is already collapsed" if is_collapsed?
+        component.click
+      end
+
+      def is_expanded?
+        component["aria-expanded"] == "true"
+      end
+
+      def is_collapsed?
+        !is_expanded?
+      end
+
+      def option(selector)
+        within("#d-menu-portals") { find(selector) }
+      end
+    end
+  end
+end