Pass ztp_stack var to trigger_ztp_configuration

New variable required to generate ZTP configuration.
Note that we can only pass strings with extra_vars in AWX API (no list
or dict).

JIRA INFRA-458 #action In Progress

app/tasks.py

@@ -120,11 +120,13 @@ def trigger_vm_creation(name, interface, memory, cores):
 
 def trigger_ztp_configuration(host):
     """Trigger a job to generate a switch ZTP configuration"""
+    ztp_stack = ",".join([item.serial_number for item in host.stack_members()])
     extra_vars = [
         f"ztp_host={host.name}",
         f"ztp_ip={host.main_interface.ip}",
         f"ztp_mac={host.main_interface.mac}",
         f"ztp_model={host.model}",
+        f"ztp_stack='{ztp_stack}'",
     ]
     job_template = current_app.config["AWX_ZTP_CONFIGURATION"]
     current_app.logger.info(