Fix possible startup error by loading plone.app.contentrules zcml (#1645

)

Fix possible startup error by explicitly loading ``plone.app.contentrules`` zcml.

Also: only load code related to contentrules when this package is available.
Fixes #1644
But reported here at first:
https://community.plone.org/t/plone-6-0-5-soft-released/17490/3?u=mauritsvanrees

news/1644.bugfix

@@ -0,0 +1,3 @@
+Fix possible startup error by explicitly loading ``plone.app.contentrules`` zcml.
+Also: only load code related to contentrules when this package is available.
+[maurits]

src/plone/restapi/serializer/controlpanels/configure.zcml

@@ -1,11 +1,15 @@
 <configure
     xmlns="http://namespaces.zope.org/zope"
+    xmlns:zcml="http://namespaces.zope.org/zcml"
     i18n_domain="plone.restapi"
     >
 
   <adapter factory=".ControlpanelSerializeToJson" />
   <adapter factory=".ControlpanelSummarySerializeToJson" />
   <adapter factory=".types.DexterityTypesControlpanelSerializeToJson" />
-  <adapter factory=".rules.ContentRulesControlpanelSerializeToJson" />
+  <adapter
+      factory=".rules.ContentRulesControlpanelSerializeToJson"
+      zcml:condition="installed plone.app.contentrules"
+      />
 
 </configure>

src/plone/restapi/services/configure.zcml

@@ -32,7 +32,6 @@
   <include package=".registry" />
   <include package=".relations" />
   <include package=".roles" />
-  <include package=".rules" />
   <include package=".search" />
   <include package=".system" />
   <include package=".sources" />
@@ -63,4 +62,8 @@
       package=".tiles"
       zcml:condition="installed plone.tiles"
       />
+  <include
+      package=".rules"
+      zcml:condition="installed plone.app.contentrules"
+      />
 </configure>

src/plone/restapi/services/controlpanels/configure.zcml

@@ -60,6 +60,7 @@
       factory="plone.restapi.controlpanels.rules.ContentRulesControlpanel"
       provides="plone.restapi.controlpanels.interfaces.IContentRulesControlpanel"
       name="content-rules"
+      zcml:condition="installed plone.app.contentrules"
       />
 
   <configure zcml:condition="have plone-5">

src/plone/restapi/services/rules/configure.zcml

@@ -3,6 +3,8 @@
     xmlns:plone="http://namespaces.plone.org/plone"
     >
 
+  <include package="plone.app.contentrules" />
+
   <plone:service
       method="GET"
       factory=".get.ContentRulesGet"