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.

Start at the create_blob_from_bytes entry point and review how blob uploads currently receive byte content. Define the source and target encoding parameters and verify that conversion occurs during upload, including the UTF-8 and UTF-16 formats needed for Azure SQL PolyBase.

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