Function reqTokenForWifiAp

reqTokenForWifiAp(): Promise<string>

Request token to device register
This api is used for registerWifiApDevice

Returns
Success and failure details as a result
- in case OK: token string
- in case NG: error message
Example
```
iot-device-sdk.reqTokenForWifiAp().then(
  (okRes: any) => {
    console.log("Token: " + okRes)
  },
  (errRes) => {
    console.log(errRes)
  }
)
```
Returns Promise<string>