[Navigation Tree] Move "nav up" arrow down one item (#3581)

* moved nav up arrow down one tree item and updated icon
* cleaned up css to be more targeted for up arrow

Co-authored-by: Deep Tailor <deep.j.tailor@nasa.gov>
Co-authored-by: charlesh88 <charlesh88@gmail.com>

src/ui/layout/mct-tree.scss

@@ -57,6 +57,14 @@
     overflow-x: hidden;
     overflow-y: auto;
 
+    .icon-arrow-nav-to-parent {
+        visibility: hidden;
+
+        &.is-enabled {
+            visibility: visible;
+        }
+    }
+
     li {
         position: relative;
         &[class*="__item-h"] {
@@ -99,6 +107,14 @@
         &.is-context-clicked {
             box-shadow: inset $colorItemTreeSelectedBg 0 0 0 1px;
         }
+
+        .icon-arrow-nav-to-parent {
+            visibility: hidden;
+
+            &.is-enabled {
+                visibility: visible;
+            }
+        }
     }
 }