Retrieve a request to migrate an account to the owned brand. Note that the brand must be configured to allow migrations. The three statuses are 'PENDING', 'COMPLETE', and 'ERROR'. If the request is 'COMPLETE', then the account successfully migrated. If the request is 'PENDING', it will be migrated at the given `migrationDate.` The 'ERROR' status means an error occurred, and more information can be found in the `statusMessage`.