Improve support and documentation for working with external libraries

[davydog187]

Lua has a large ecosystem of off the shelf libraries, available through the Lua package manager, https://luarocks.org/

Lua should have an easy way to work with Lua packages, possibly even a tight integration with Lua rocks via a mix task that can pull down and vendor Lua packages.

Additionally, we should document how to integrate with popular packages, like luassert