Allow to choose the PREFERRED_ENCODING order

Hello ,
Since v1.8.0, the preferred compression method is brotli.

I'm using the Compression module in an aws lambda behind Api Gateway but brotli compression is not handled by it.
As most of the clients are now passing ` gzip, deflate, br` as default `Accept-Encoding` header this cause decompression errors.

It would be nice to have an option that allows to change the order of the PREFERRED_ENCODING array to be able to have gzip as preferred compression method.