Migrate Collapse/Open Resource Tree to React (#733)

Co-authored-by: Steve Faulkner <southpolesteve@gmail.com>

less/documentDB.less

@@ -2099,7 +2099,7 @@ a:link {
   display: flex;
   flex: 1 1 auto;
   overflow-x: auto;
-  overflow-y: auto;
+  overflow-y: hidden;
   height: 100%;
 }
 
@@ -3085,3 +3085,7 @@ settings-pane {
     padding-left: @SmallSpace;
   }
 }
+.hiddenMain {
+  visibility: hidden;
+  height: 0px;
+}

less/tree.less

@@ -3,6 +3,7 @@
 
 .resourceTree {
     height: 100%;
+    width: 20%;
     flex: 0 0 auto;
     .main {
         height: 100%;