Add skeleton for instance statistics

- Adds the controller and blank
page for instance statistics

app/controllers/admin/instance_statistics_controller.rb

+# frozen_string_literal: true
+
+class Admin::InstanceStatisticsController < Admin::ApplicationController
+  before_action :check_feature_flag
+
+  def index
+  end
+
+  def check_feature_flag
+    render_404 unless Feature.enabled?(:instance_analytics)
+  end
+end

app/views/admin/instance_statistics/index.html.haml

+- breadcrumb_title _("Instance Statistics")
+- page_title _("Instance Statistics")
+
+#js-instance-statistics-app

app/views/layouts/nav/sidebar/_admin.html.haml

@@ -69,6 +69,11 @@
             = link_to admin_cohorts_path, title: _('Cohorts') do
               %span
                 = _('Cohorts')
+          - if Feature.enabled?(:instance_statistics)
+            = nav_link(controller: :instance_statistics) do
+              = link_to admin_instance_statistics_path, title: _('Instance Statistics') do
+                %span
+                  = _('Instance Statistics')
 
       = nav_link(controller: admin_monitoring_nav_links) do
         = link_to admin_system_info_path, data: { qa_selector: 'admin_monitoring_link' } do

config/feature_flags/development/instance_statistics.yml

+---
+name: instance_statistics
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/40583
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/241711
+group: group::analytics
+type: development
+default_enabled: false
\ No newline at end of file

locale/gitlab.pot

@@ -13234,6 +13234,9 @@ msgstr[1] ""
 msgid "Instance Configuration"
 msgstr ""
 
+msgid "Instance Statistics"
+msgstr ""
+
 msgid "Instance administrators group already exists"
 msgstr ""