feat(template) Add a method to alter template attributes

This method allows to set some attributes as mandatory, readonly or
 hidden.
It may be done in an other way later but this will allow to start
 testing it in public-forms plugin

issue #5854

include/class_template.inc

@@ -142,6 +142,35 @@ class template
     return $this->attributes;
   }
 
+  function alterAttributes($mandatories, $readonly, $hidden)
+  {
+    foreach ($mandatories as $class => $attrs) {
+      foreach ($attrs as $attr) {
+        if (!in_array($attr, $this->attributes[$class])) {
+          $this->attributes[$class][] = $attr;
+        }
+        $this->tabObject->by_object[$class]->attributesAccess[$attr]->setRequired(TRUE);
+      }
+    }
+    foreach ($readonly as $class => $attrs) {
+      foreach ($attrs as $attr) {
+        if (!in_array($attr, $this->attributes[$class])) {
+          $this->attributes[$class][] = $attr;
+        }
+        $this->tabObject->by_object[$class]->attributesAccess[$attr]->setDisabled(TRUE);
+      }
+    }
+    foreach ($hidden as $class => $attrs) {
+      foreach ($attrs as $attr) {
+        if (!in_array($attr, $this->attributes[$class])) {
+          $this->attributes[$class][] = $attr;
+        }
+        $this->tabObject->by_object[$class]->attributesAccess[$attr]->setDisabled(TRUE);
+        $this->tabObject->by_object[$class]->attributesAccess[$attr]->setVisible(FALSE);
+      }
+    }
+  }
+
   function serialize()
   {
     $ret = array();