PB-500 increase z index of content type options

Author: paras89

app/code/Magento/PageBuilder/view/adminhtml/web/css/source/content-type/_preview.less

@@ -372,7 +372,7 @@
     transform: translate(0, -50%);
     transition: opacity 200ms, visibility 200ms;
     visibility: hidden;
-    z-index: 105;
+    z-index: 1000;
 
     &.pagebuilder-options-middle {
         right: 50%;