Support for storage class

[LombardiDaniel]

Support for storage class when creating a backup destination, on the internal/integration/storage/s3.go it would be a simple change:

func (Client) S3Upload(
	accessKey, secretKey, region, endpoint, bucketName, storageClass, key string,
	fileReader io.Reader,
) (int64, error) {
	s3Client, err := createS3Client(
		accessKey, secretKey, region, endpoint,
	)
	if err != nil {
		return 0, err
	}

	key = strutil.RemoveLeadingSlash(key)
	contentType := strutil.GetContentTypeFromFileName(key)

	uploader := s3manager.NewUploaderWithClient(s3Client)
	_, err = uploader.Upload(&s3manager.UploadInput{
		Bucket:       aws.String(bucketName),
		Key:          aws.String(key),
		Body:         fileReader,
		ContentType:  aws.String(contentType),
		StorageClass: aws.String(storageClass),
	})
	if err != nil {
		return 0, fmt.Errorf("failed to upload file to S3: %w", err)
	}

	fileHead, err := s3Client.HeadObject(&s3.HeadObjectInput{
		Bucket: aws.String(bucketName),
		Key:    aws.String(key),
	})
	if err != nil {
		return 0, fmt.Errorf("failed to get uploaded file info from S3: %w", err)
	}
	fileSize := *fileHead.ContentLength

	return fileSize, nil
}

Didn't really look into much more than that though