IBX-10957: Fixed notifications popup options (#1774)

Author: albozek

src/bundle/Resources/public/scss/_notification-actions-popup-menu.scss

@@ -0,0 +1,5 @@
+.ibexa-notification-actions-popup-menu {
+    &.ibexa-popup-menu {
+        z-index: 10260;
+    }
+}

src/bundle/Resources/public/scss/ibexa.scss

@@ -81,6 +81,7 @@
 @import 'dashboard';
 @import 'picker';
 @import 'notifications-modal';
+@import 'notification-actions-popup-menu';
 @import 'side-panel';
 @import 'admin.section-view';
 @import 'content-tree';