data-compiler: generate data requirements for .lua files automatically

[dbartolini]

When given any .lua resource, like:

require "units/cat"

function you_know()
    World.spawn_unit(w, "units/table")
    ...
end

The data-compiler should able to figure out its two requirements: "units/cat" and "units/table".

Current status:

• [x] find .lua requirements for require() function calls (https://github.com/crownengine/crown/commit/82a3c4f648e5260997c19a935a9b8f6917eead50)
• [ ] #155