CopyPollerBlobClient type
定義 BlobClient 所需的操作，這些操作是 BlobClient.beginCopyFromURL 回傳的輪詢器運作所需的。
type CopyPollerBlobClient = Pick<BlobClient, "abortCopyFromURL" | "getProperties"> & { startCopyFromURL(copySource: string, options?: BlobStartCopyFromURLOptions) => Promise<BlobBeginCopyFromURLResponse> }