COMPASS-1687: Fix editable element z-indexes

Author: durran

src/internal-packages/crud/styles/editable-element-field.less

@@ -3,15 +3,15 @@
   border: none;
   padding-left: 1px;
   -webkit-user-select: text;
-  max-width: 15vw; 
+  max-width: 15vw;
   text-overflow: ellipsis;
   white-space: nowrap;
   overflow: hidden;
 
   &-is-editing {
     border: 1px solid @gray3;
     box-shadow: 0px 2px 4px 0px rgba(0,0,0,0.2);
-    z-index: 10;
+    z-index: 200;
     margin-top: -1px;
     margin-bottom: -1px;
   }

src/internal-packages/crud/styles/editable-element-value.less

@@ -57,7 +57,7 @@
   &-is-editing {
     border: 1px solid @gray3;
     box-shadow: 0px 2px 4px 0px rgba(0,0,0,0.2);
-    z-index: 10;
+    z-index: 200;
     margin-top: -1px;
     margin-bottom: -1px;
   }

src/internal-packages/crud/styles/element.less

@@ -22,6 +22,8 @@
     vertical-align: top;
     -webkit-user-select: text;
     flex-grow: 3;
+    z-index: 50;
+    position: relative;
 
     &-is-string {
       color: steelblue;