EventHistoryQuery: Provide `hostgroup_name' as alternative to `hostgroup'

This can't be queried though until #7274 has been resolved.

refs #8613

modules/monitoring/library/Monitoring/Backend/Ido/Query/EventHistoryQuery.php

@@ -44,6 +44,7 @@ class EventHistoryQuery extends IdoQuery
         ),
         'hostgroups' => array(
             'hostgroup'             => 'hgo.name1 COLLATE latin1_general_ci',
+            'hostgroup_name'        => 'hgo.name1'
         ),
         'hosts' => array(
             'host_display_name'     => 'CASE WHEN sh.display_name IS NOT NULL THEN sh.display_name ELSE h.display_name END'

modules/monitoring/library/Monitoring/DataView/EventHistory.php

@@ -22,6 +22,7 @@ class EventHistory extends DataView
             'host_display_name',
             'service_description',
             'service_display_name',
+            'hostgroup_name',
             'object_type',
             'timestamp',
             'state',