Increased zindex of layout nav

This fixes issues where group inputs would be above the dropdown in the nav

Closes #17524

app/assets/stylesheets/framework/nav.scss

@@ -196,7 +196,7 @@
   position: fixed;
   top: $header-height;
   width: 100%;
-  z-index: 3;
+  z-index: 11;
   background: $background-color;
   border-bottom: 1px solid $border-color;
   transition-duration: .3s;