Configure nginx with SSI and enable by default

[jrrdnx]

Looking to use server side includes and came across this pull request for Valet from 2018: laravel/valet#517

Attempted to enable this for Herd but this results in an unknown directive "ssi" error in the logs. After some digging, it appears nginx is configured without http_ssi_module by default.

% /Applications/Herd.app/Contents/Resources/nginx-arm64 -V
nginx version: nginx/1.25.4
built with OpenSSL 3.2.1 30 Jan 2024
TLS SNI support enabled
configure arguments: [...] --without-http_ssi_module [...]

Would love to have this included and enabled by default.