Context: https://caddy.community/t/including-files-scripts/15050/4

Right now, the templates module is inflexible in that only functions the functions registered by Caddy itself are available.

A good refactor would be to make it possible to pass an optional array of modules in the http.handlers.templates.functions.* namespace which get invoked at Provision() time to register additional functions.