Return backup configuration file data

Example response

{
  "data": {
    "backup_config": {
      "backup_daily_enable": 1,
      "backup_daily_retention": 5,
      "backup_monthly_dates": "1,15,22",
      "backup_monthly_retention": 5,
      "backup_weekly_day": "1,3,5",
      "backup_weekly_retention": 4,
      "backupaccts": 1,
      "backupbwdata": 1,
      "backupdays": "0,2,4,6",
      "backupdir": "/backup",
      "backupenable": 1,
      "backupfiles": 1,
      "backuptype": "compressed",
      "check_min_free_space": 1,
      "errorthreshhold": 3,
      "gziprsyncopts": "--rysncable",
      "keeplocal": 1,
      "maximum_restore_timeout": 21600,
      "maximum_timeout": 7200,
      "min_free_space": 1024,
      "min_free_space_unit": "MB",
      "mysqlbackup": "accounts",
      "prebackup": 1,
      "remote_restore_staging_dir": "/backup"
    }
  },
  "metadata": {
    "command": "backup_config_get",
    "reason": "OK",
    "result": 1,
    "version": 1
  }
}