Add project level MR analytics FE

ee/app/assets/javascripts/pages/projects/analytics/merge_request_analytics/index.js

+import initMergeRequestAnalyticsApp from 'ee/analytics/merge_request_analytics';
+
+document.addEventListener('DOMContentLoaded', initMergeRequestAnalyticsApp);

ee/app/views/projects/analytics/merge_request_analytics/show.html.haml

+- page_title _("Merge Request Analytics")
+
+#js-merge-request-analytics-app