[Feature] Add SMART test result to disks

[tomaae]

request from https://community.home-assistant.io/t/truenas-integration/410431/33

curl -X GET -H "Authorization: Bearer " http:///api/v2.0/smart/test/results

{
  "tests": [
   {
    "num": 1,
    "description": "Background short",
    "status_verbose": "Completed",
    "segment_number": 64,
    "lifetime": 65535,
    "lba_of_first_error": null,
    "status": "SUCCESS"
   },
   {
    "num": 2,
    "description": "Background short",
    "status_verbose": "Completed",
    "segment_number": 64,
    "lifetime": 3,
    "lba_of_first_error": null,
    "status": "SUCCESS"
   },
   {
    "num": 3,
    "description": "Reserved(7)",
    "status_verbose": "Completed",
    "segment_number": 48,
    "lifetime": 3,
    "lba_of_first_error": null,
    "status": "SUCCESS"
   },
   {
    "num": 4,
    "description": "Background short",
    "status_verbose": "Completed",
    "segment_number": 64,
    "lifetime": 1,
    "lba_of_first_error": null,
    "status": "SUCCESS"
   }
  ],
  "current_test": null,
  "identifier": "{serial_lunid}S0M35Q0T_5000c5007703628b",
  "name": "sdu",
  "subsystem": "scsi",
  "number": 16704,
  "serial": "S0M35Q0T",
  "lunid": "5000c5007703628b",
  "size": 600127266816,
  "description": "",
  "transfermode": "Auto",
  "hddstandby": "ALWAYS ON",
  "advpowermgmt": "DISABLED",
  "togglesmart": true,
  "smartoptions": "",
  "expiretime": null,
  "critical": null,
  "difference": null,
  "informational": null,
  "model": "ST600MM0006",
  "rotationrate": 10000,
  "type": "HDD",
  "zfs_guid": "4331329417788955794",
  "bus": "SCSI",
  "devname": "sdu",
  "enclosure": null,
  "supports_smart": null,
  "pool": null,
  "disk": "sdu"
 }