[erp5_web_renderjs_ui] Add WIP less CSS source code

bt5/erp5_web_renderjs_ui/SkinTemplateItem/portal_skins/erp5_web_renderjs_ui/erp5css.less.xml

+<?xml version="1.0"?>
+<ZopeData>
+  <record id="1" aka="AAAAAAAAAAE=">
+    <pickle>
+      <global name="File" module="OFS.Image"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>__name__</string> </key>
+            <value> <string>erp5css.less</string> </value>
+        </item>
+        <item>
+            <key> <string>content_type</string> </key>
+            <value> <string>text/plain</string> </value>
+        </item>
+        <item>
+            <key> <string>precondition</string> </key>
+            <value> <string></string> </value>
+        </item>
+        <item>
+            <key> <string>title</string> </key>
+            <value> <string></string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+</ZopeData>