[FIX] web_advanced_search: Implement 'Add Advanced Filter' for owl widgets (pivot, graph)

Steps to reproduce:

1. Go to any Pivot or Graph view.
2. Open the filter menu.

Result:

'Add Advanced Filter' option is not there

web_advanced_search/static/src/xml/FilterMenu.xml

@@ -10,4 +10,9 @@
             <AdvancedFilterItem />
         </CustomFilterItem>
     </t>
+    <t t-inherit="web.FilterMenu" t-inherit-mode="extension" owl="1">
+        <CustomFilterItem position="after">
+            <AdvancedFilterItem />
+        </CustomFilterItem>
+    </t>
 </templates>