slapos_jio: Add script to include a message on the login page

This is usefull for display warning related to mantainence or changes of policies.

master/bt5/slapos_jio/SkinTemplateItem/portal_skins/slapos_hal_json_style/WebSection_getLoginWarningMessage.py

+return ""

master/bt5/slapos_jio/SkinTemplateItem/portal_skins/slapos_hal_json_style/WebSection_getLoginWarningMessage.xml

+<?xml version="1.0"?>
+<ZopeData>
+  <record id="1" aka="AAAAAAAAAAE=">
+    <pickle>
+      <global name="PythonScript" module="Products.PythonScripts.PythonScript"/>
+    </pickle>
+    <pickle>
+      <dictionary>
+        <item>
+            <key> <string>Script_magic</string> </key>
+            <value> <int>3</int> </value>
+        </item>
+        <item>
+            <key> <string>_bind_names</string> </key>
+            <value>
+              <object>
+                <klass>
+                  <global name="NameAssignments" module="Shared.DC.Scripts.Bindings"/>
+                </klass>
+                <tuple/>
+                <state>
+                  <dictionary>
+                    <item>
+                        <key> <string>_asgns</string> </key>
+                        <value>
+                          <dictionary>
+                            <item>
+                                <key> <string>name_container</string> </key>
+                                <value> <string>container</string> </value>
+                            </item>
+                            <item>
+                                <key> <string>name_context</string> </key>
+                                <value> <string>context</string> </value>
+                            </item>
+                            <item>
+                                <key> <string>name_m_self</string> </key>
+                                <value> <string>script</string> </value>
+                            </item>
+                            <item>
+                                <key> <string>name_subpath</string> </key>
+                                <value> <string>traverse_subpath</string> </value>
+                            </item>
+                          </dictionary>
+                        </value>
+                    </item>
+                  </dictionary>
+                </state>
+              </object>
+            </value>
+        </item>
+        <item>
+            <key> <string>_params</string> </key>
+            <value> <string></string> </value>
+        </item>
+        <item>
+            <key> <string>id</string> </key>
+            <value> <string>WebSection_getLoginWarningMessage</string> </value>
+        </item>
+      </dictionary>
+    </pickle>
+  </record>
+</ZopeData>

master/bt5/slapos_jio/SkinTemplateItem/portal_skins/slapos_hal_json_style/login_form.zpt

@@ -27,6 +27,11 @@
 
     <div role="main" class="ui-container gadget-content">
       <article>
+        <div class="ui-field-contain">
+           <section>
+              <span tal:replace="structure here/WebSection_getLoginWarningMessage"></span>
+          </section>
+        </div>
          <div class="ui-field-contain">
            <section>
             <tal:block tal:condition="exists: request/portal_status_message">