Add `application/zstd` support for http requests/responses

[mdedetrich]

zstd is a new compression that is far superior to gzip/lzma in every way and it has also been published as https://www.rfc-editor.org/rfc/rfc8478 as application/zstd which means that http requests/responses can be compressed/decompressed via std.

In terms of browsers, Chromium and Firefox have already added support for zstd compression/decompression, which means that only Safari is needed to have support in all mainstream browsers.

Requires apache/pekko#2404 to be completed and released, at which point we need to add the various header entries.

[He-Pin]

Nice, we are actually using zstd at Mtop(our api gateway) at Taobao, with https://github.com/luben/zstd-jni

[mdedetrich]

Nice, we are actually using zstd at Mtop(our api gateway) at Taobao, with https://github.com/luben/zstd-jni

Glad to hear that zstd-jni is being used in production without issues as thats what I am using to implement the stream in pekko-streams.