Revert "fix: Remove pointless Maintenance and Announcement apps (#35852)"

This reverts commit 9274852f2d.

cms/templates/maintenance/container.html

@@ -0,0 +1,33 @@
+<%page expression_filter="h"/>
+<%inherit file="base.html" />
+<%namespace name='static' file='../static_content.html'/>
+<%!
+from django.urls import reverse
+from openedx.core.djangolib.js_utils import js_escaped_string
+%>
+<%block name="title">${view['name']}</%block>
+<%block name="viewtitle">
+<h3 class="info-course">
+    <span>${view['name']}</span>
+</h3>
+</%block>
+
+<%block name="viewcontent">
+<section class="container maintenance-content">
+    <%include file="_${view['slug']}.html"/>
+</section>
+</%block>
+
+<%block name="header_extras">
+% for template_name in ["force-published-course-response"]:
+<script type="text/template" id="${template_name}-tpl">
+    <%static:include path="js/maintenance/${template_name}.underscore" />
+</script>
+% endfor
+</%block>
+
+<%block name="requirejs">
+  require(["js/maintenance/${view['slug'] | n, js_escaped_string}"], function(MaintenanceFactory) {
+      MaintenanceFactory("${reverse(view['url']) | n, js_escaped_string}");
+  });
+</%block>