Job splitting access logic and more feature development

*allow sharding with prompts and schedules
*modify create_unified_job contract to pass class & parent_field name
*make parent field name instance method & set sharded UJT field
*access methods made compatible with job sharding
*move shard job special logic from task manager to workflows
*save sharded job prompts to workflow job exclusively
*allow using sharded jobs in workflows

awx/main/models/inventory.py

@@ -1647,8 +1647,7 @@ class InventoryUpdate(UnifiedJob, InventorySourceOptions, JobNotificationMixin,
         null=True
     )
 
-    @classmethod
-    def _get_parent_field_name(cls):
+    def _get_parent_field_name(self):
         return 'inventory_source'
 
     @classmethod