add id column to model

Change-Id: I0c62ef3c296f8aa1ce8b924cf88f569c48dc198f
Reviewed-on: https://gerrit.libreoffice.org/61666
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

sw/uiconfig/swriter/ui/inserttable.ui

@@ -27,6 +27,8 @@
     <columns>
       <!-- column-name text -->
       <column type="gchararray"/>
+      <!-- column-name id -->
+      <column type="gchararray"/>
     </columns>
   </object>
   <object class="GtkDialog" id="InsertTableDialog">