erp5_pdm: Provide a count_method on Resource Modules by default.

count_method was removed from Base_viewFieldLibrary/my_view_mode_module_listbox
used by Resource Module ListBox (76282344) for performance issues when
countFolder is called with a Module containing > ~50k documents but this
should not be relevant for Resource Modules.

bt5/erp5_pdm/SkinTemplateItem/portal_skins/erp5_pdm/Base_viewPDMFieldLibrary/my_view_mode_resource_module_listbox.xml

@@ -12,6 +12,7 @@
               <list>
                 <string>all_columns</string>
                 <string>columns</string>
+                <string>count_method</string>
                 <string>domain_root_list</string>
                 <string>domain_tree</string>
                 <string>portal_types</string>
@@ -192,6 +193,12 @@
                       </list>
                     </value>
                 </item>
+                <item>
+                    <key> <string>count_method</string> </key>
+                    <value>
+                      <persistent> <string encoding="base64">AAAAAAAAAAQ=</string> </persistent>
+                    </value>
+                </item>
                 <item>
                     <key> <string>domain_root_list</string> </key>
                     <value>
@@ -292,4 +299,17 @@
       </dictionary>
     </pickle>
   </record>
+  <record id="4" aka="AAAAAAAAAAQ=">
+    <pickle>
+      <global name="Method" module="Products.Formulator.MethodField"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>method_name</string> </key>
+            <value> <string>countFolder</string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
 </ZopeData>