Save tree state 'per tree'

- Separate save state for Part and Stock tree

InvenTree/part/templates/part/part_app_base.html

@@ -34,7 +34,11 @@ InvenTree | Part List
 {% block js_ready %}
 {{ block.super }}
     loadTree("{% url 'api-part-tree' %}",
-             "#part-tree");
+            "#part-tree",
+            {
+                name: 'part',
+            }
+    );
 
     $("#toggle-part-tree").click(function() {
         toggleSideNav("#sidenav");