Feature zstd support for http-content-encoding

[willfarrell]

Does anyone need this?

Downside, adds 2MB to the packages, zstd isn't smaller than brotli in my testing.

Will leave as PR, only Chrome supports right now.

TODO

• Remove dep and use native API when supported: https://github.com/nodejs/node/issues/48412
• node 23.x supports zstd (https://nodejs.org/api/zlib.html#zlibcreatezstdcompressoptions)