HostMetricSummaryMonthly command + views + scheduled task (#13999)

Co-authored-by: Alan Rominger <arominge@redhat.com>

awx/main/conf.py

@@ -862,6 +862,15 @@ register(
     category_slug='system',
 )
 
+register(
+    'HOST_METRIC_SUMMARY_TASK_LAST_TS',
+    field_class=fields.DateTimeField,
+    label=_('Last computing date of HostMetricSummaryMonthly'),
+    allow_null=True,
+    category=_('System'),
+    category_slug='system',
+)
+
 register(
     'AWX_CLEANUP_PATHS',
     field_class=fields.BooleanField,