Lazy load images in mobile sidebar & header

Closes #38276

app/assets/javascripts/main.js

@@ -302,7 +302,10 @@ $(function () {
     return $container.remove();
   // Commit show suppressed diff
   });
-  $('.navbar-toggle').on('click', () => $('.header-content').toggleClass('menu-expanded'));
+  $('.navbar-toggle').on('click', () => {
+    $('.header-content').toggleClass('menu-expanded');
+    gl.lazyLoader.loadCheck();
+  });
   // Show/hide comments on diff
   $body.on('click', '.js-toggle-diff-comments', function (e) {
     var $this = $(this);

app/assets/javascripts/right_sidebar.js

@@ -43,6 +43,8 @@ import Cookies from 'js-cookie';
           $allGutterToggleIcons.removeClass('fa-angle-double-left').addClass('fa-angle-double-right');
           $('aside.right-sidebar').removeClass('right-sidebar-collapsed').addClass('right-sidebar-expanded');
           $('.page-with-sidebar').removeClass('right-sidebar-collapsed').addClass('right-sidebar-expanded');
+
+          gl.lazyLoader.loadCheck();
         }
         if (!triggered) {
           return Cookies.set("collapsed_gutter", $('.right-sidebar').hasClass('right-sidebar-collapsed'));