Add recoding possibility to create_blob_from_bytes

### Which service(blob, file, queue) does this issue concern?
Blob

### What problem was encountered?

During the creation of a blob, it would be useful if you could add the encoding of the file ,together with the desired encoding. So if you have a file stored that is in big5 encoding, but you want it to be in utf-8, you would simple add two parameters and that could be used.

Currently, one has to re-encode the file themselves, which is sometimes time consuming with large files.

### Why should this be implemented?
To be able to create a table in azure sql dwh using polybase, the only allowed encodings are utf-8 and utf-16. This means you have to re-encode all the files yourself first before creation tables for these. But enabling this feature would make the process way easier, since then you would have them converted during uploading.

Commencez au point d’entrée create_blob_from_bytes et examinez comment les téléversements de blobs reçoivent actuellement le contenu en octets. Définissez les paramètres d’encodage source et cible et vérifiez que la conversion s’effectue pendant le téléversement, y compris les formats UTF-8 et UTF-16 requis pour Azure SQL PolyBase.

Rédigé par le modèle d'indexation à partir du texte de l'issue.