Add zstd http channel output compression

Zstd is currently the best compression available:

• zstd is supported for a year now in all major browsers
• zstd uses less CPU
• It achieves better or on-par compression than brotli and gzip
• It uses way less real time to achieve better compression

Hint: Browsers  will only annouonce zstd support on https connections.

Here is a comparison on AIX for a 7 MiB javascript file:

Algo     Level    Time        Size      Size %
Baseline             0      7666149    100,0000%
gzip       6       466      2036606     26,5662%
zstd       3        77      2085469     27,2036%

This one is for Linux on x64:

Algo     Level    Time        Size      Size %
Baseline             0      7666149    100,0000%
gzip       6       487      2036606     26,5662%
zstd       3        73      2097140     27,3558%

When a dictionary is added, the compression gets even better than that.
 

Actual CPU usage on a Mac:

$ time zstd -3 --keep chunk-vendors.bundle.js -o chunk-vendors.bundle.js.3.zstd
chunk-vendors.bundle.js : 27.20%   (  7.31 MiB =>   1.99 MiB, chunk-vendors.bundle.js.3.zstd)
zstd -3 --keep chunk-vendors.bundle.js -o chunk-vendors.bundle.js.3.zstd 0.03s user 0.01s system 56% cpu 0.073 total

$ time gzip  -6 -k chunk-vendors.bundle.js; ls -lF chunk-vendors.bundle.js.gz
gzip -6 -k chunk-vendors.bundle.js  0.25s user 0.01s system 98% cpu 0.263 total
-rw-r--r--@ 1 user  group  2035493 26 Nov 13:50 chunk-vendors.bundle.js.gz

https://github.com/OpenLiberty/open-liberty/issues/30297