401 Unauthorized when calling metadata-schemas API

[k3-yasuda]

#87
Due to the impact of the above PR, accessing the metadata-schemas API returns a 401 status code.

The cause is that the access token being used is for the Azure API Center data plane API, not for ARM. A process to obtain an ARM access token is required.

Below are the settings at the time the error occurred.

{
  "dataApiHostName": "xxxxxxxxxxxxx.data.eastus.azure-apicenter.ms/workspaces/default",
  "title": "API portal",
  "authentication": {
    "clientId": "xxxxxxxxxxxxx",
    "tenantId": "xxxxxxxxxxxxx",
    "scopes": [
      "https://azure-apicenter.net/user_impersonation"
    ],
    "authority": "https://login.microsoftonline.com/"
  }
}