UI: redesigned settings/members (#23804)

This PR is a first step towards private groups. It redesigns settings/members area of a channel and also drops the "about" page which is now mixed into settings.

This commit is also:
- introducing chat-form, a small DSL to create forms, ideally I would want something in core for this
- introducing a DToggleSwitch page object component to simplify testing toggles
- migrating various components to gjs

spec/system/page_objects/components/d_toggle_switch.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module PageObjects
+  module Components
+    class DToggleSwitch < PageObjects::Components::Base
+      attr_reader :context
+
+      def initialize(context)
+        @context = context
+      end
+
+      def component
+        find(@context, visible: :all).native
+      end
+
+      def toggle
+        actionbuilder = page.driver.browser.action # workaround zero height button
+        actionbuilder.click(component).perform
+      end
+    end
+  end
+end