To import luarocks properly to pkgsrc, we should modify our infrastructure
for installing Lua modules. Specifically, our lang/lua/module.mk should
create INSTALL hooks for generating Rock metadata so that pkgsrc-installed
Lua modules can be recognized by luarocks.

See:
https://github.com/luarocks/luarocks/blob/main/docs/integrating_distro_modules_with_luarocks.md
