[feature] Update role configuration when somebody changes his username.

[heming6666]

Since we use username (such as 'Tom', 'Jack') in the configuration of role info, if somebody changes his username (for example, from 'Tom' to 'Tom2'), the original configuration would be out-of-date. So maybe we need a kind of mechanism to remind the user or the someone else to update the configuration.

"role": {
    "version": 1,
    "roles": [
      {
        "name": "committer",
        "description": "Committer of the project",
        "users": [ "Tom", "Jack" ],
        "commands": [ "/difficulty"]
      }
    ]
  }

[kitewu]

This is the same as file-private-config hypertrons#211

[frank-zsy]

Maybe not exactly same, because we can not get webhook if a user change his login, so we need a regular check for it.