CompressionLayer add zstd support

[beckend]

Feature Request

Motivation

It's new, but it's starting to pick up.
Here is a curl request:

curl --compressed http://whatever.com/my/endpoint
> GET /my/endpoint HTTP/1.1
> Host: whatever.com
> User-Agent: curl/7.87.0
> Accept: */*
> Accept-Encoding: deflate, gzip, br, zstd

It's also available in envoy proxy serving such requests.
https://github.com/envoyproxy/envoy/tree/main/examples/zstd

[davidpdrsn]

That should be quite straightforward seeing as async-compression already supports it.