Issue a verification H5 link

A gateway-provided action with no upstream equivalent. An H5 page must not carry an sk- key, so the gateway issues a temporary rt_ token that only allows the liveness actions and is bound to the issuing channel. Send H5Link to the user; once it expires, issue a new one.

curl -X POST "https://jiniu.ai/api/material?Action=CreateRealValidateH5" \  -H "Content-Type: application/json" \  -d '{}'

{
  "ResponseMetadata": {
    "RequestId": "…",
    "Action": "CreateRealValidateH5"
  },
  "Result": {
    "H5Link": "https://jiniu.ai/rv?t=rt_xxxxxxxx",
    "ExpiresIn": 3600
  }
}