Add chasis locate action

Would be great if a node actions list will contain action for activating chasis locate led via IPMI. Now, for do this action, we need to query IPMI credentials from MaaS API and run command like "ipmi-chassis -h $host_ip -u $ipmi_username -p $ipmi_pass --chassis-identify=60". This button and respectively API endpoint can help to perform Inventorisation process and automatically find hardware by its MaaS node representation. Example of actions: enable led, disable led, enable led for n seconds.