Add externalid for ticket templates

Author: cconard96

src/Ticket.php

@@ -3521,6 +3521,7 @@ public static function getDefaultValues($entity = 0)
             '_tag_filename'             => [],
             '_actors'                   => [],
             '_contracts_id'             => 0,
+            'externalid'                => '',
         ];
     }
 

src/TicketTemplate.php

@@ -141,7 +141,11 @@ public static function getExtraAllowedFields($withtypeandcategory = false, $with
                 'type',
                 'glpi_tickets'
             )   => 'type',
-
+            $itil_object->getSearchOptionIDByField(
+                'field',
+                'externalid',
+                'glpi_tickets'
+            )   => 'externalid',
         ];
 
         if ($withtypeandcategory) {

tests/functional/ITILTemplateTest.php

@@ -233,6 +233,7 @@ public static function fieldsProvider()
                     180 => 'Internal time to resolve',
                     185 => 'Internal time to own',
                     193 => 'Contract',
+                    87 => 'External ID',
                 ],
             ], [
                 'Change',