Persist blob metadata changes

[stuartmcgillivray]

Adding await _blobStorage.SetBlobAsync(blob, cancellationToken); to persist changes to the metadata so binary data is correctly delt with when read back.

#3115

[dnfadmin]

All CLA requirements met.

[jdevillard]

why don't we use directly the blob property instead of the blob metadata for the content-type? maybe it's not available through the storage.net abstraction?

[sfmskywalker]

@stuartmcgillivray Any thoughts on @jdevillard 's suggestion?

[stuartmcgillivray]

It doesn't appear to expose that option at least through the S3 provider I am looking at.

I can see content-type is available as a header though the object returned by the s3 client but that doesn't get transfered to the Blob.

[sfmskywalker]

I checked as well, but couldn't find a way to create a Blob first and provide the stream/bytes to upload, or to provide the bytes + blob properties in one go.

Let's go with this solution for now, since at least it fixes an issue. A future SDK update might allow us to upload a blob + metadata at the same time.