message: add acrUseManagedIdentityCreds and acrUserManagedIdentityID properties to SiteConfig
diff: "description": "<code>true</code> if HTTP logging is enabled; otherwise, <code>false</code>.",
  "type": "boolean"
  },
  + "acrUseManagedIdentityCreds": {
  + "description": "Flag to use Managed Identity Creds for ACR pull",
  + "type": "boolean"
  + },
  + "acrUserManagedIdentityID": {
  + "description": "If using user managed identity, the user managed identity ClientId",
  + "type": "string"
  + },
  "logsDirectorySizeLimit": {
  "format": "int32",
  "description": "HTTP logs directory size limit.",
  