Add ability to set ContentEncoding

[jainkuniya]

Once the files are uploaded, they aren't been served in gzip.

On googling a bit, I found that it needs to be set while uploading the file, see here https://www.digitalocean.com/community/questions/how-do-i-enable-gzip-compression-on-spaces

So thought, adding this option would be a great add.

Thanks

reference: https://docs.digitalocean.com/products/spaces/how-to/set-file-metadata/

[jainkuniya]

@BetaHuhn what do you think on this?