Improvements to backblaze data transfer

[alexlipa91]

• Add support for MEDIA transfer
• Add support for photos and videos in the same folder
• Use media name instead of id
• Store media creation time as S3 object metadata (it is not possible to set the creation date in S3 since it is automatically set by the server)

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[lisad]

Closing stale pull request. It would need to have conflicts fixed if it needs to be re-opened. Pinging @ameya9 because this may have originally been a contribution from a colleague of yours.