feat(zb-experimental): implement download_ranges

[chandra-siri]

Downloads multiple byte ranges from the object into the buffers provided by user.

This interface provides option to download multiple ranges of a GCS Object
concurrently.

Example usage

        client = AsyncGrpcClient().grpc_client
        mrd = await AsyncMultiRangeDownloader.create_mrd(
            client, bucket_name="chandrasiri-rs", object_name="test_open9"
        )
        my_buff1 = open('my_fav_file.txt', 'wb')
        my_buff2 = BytesIO()
        my_buff3 = BytesIO()
        my_buff4 = any_object_which_provides_BytesIO_like_interface()
        results_arr, error_obj = await mrd.download_ranges(
            [
                (0, 100, my_buff1),
                (100, 20, my_buff2),
                (200, 123, my_buff3),
                (300, 789, my_buff4),
            ]
        )
        if error_obj:
            print("Error occurred: ")
            print(error_obj)
            print(
                "please issue call to `download_ranges` with updated"
                "`read_ranges` based on diff of (bytes_requested - bytes_written)"
            )

        for result in results_arr:
            print("downloaded bytes", result)

[chandra-siri]

@Pulkit0110 Replied to your comments, please review further. Feel free to resolve if comments sounds good.