Can you add ability to set content-encoding using the set attribute?

[GiancarloGomez]

I have an issue where we are trying to serve SVGZ files and I am using an outbound rule to set the content-type to "image.sgg+xml" but in order for the browser to work with it it also needs to know that the content-encoding is "gzip" as SVGZ are just gzipped SVGs.