Support "Accept-Encoding" header to enable response gzip compression

Spinoff from email

Accept-Encoding:

Advertises which content encoding, usually a compression algorithm, the client is able to understand
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Encoding

Could enable compression of large search results. SOLR-856 suggests that this is implemented,
but it does not work. Seems it is only implemented for replication. I’d expect this to be useful for
large /export or /stream requests. Example:
Accept-Encoding: gzip

Could be configured with the Jetty Gzip Handler