lua: add "builtins" file to consolidate registration

lua: add "builtins" file to consolidate registration

Use a single array of built-ins and provide 2 functions for
registering them:

- SCLuaLoadBuiltIn: for loading built-in modules in sandboxed
  environments.

- SCLuaRequirefBuiltIns: registers built-in modules with the standard
  package tool, allows built-ins to be loaded by output scripts that are
  not restricted

I hope to refactor the sandbox so they can use SCLuaRequirefBuiltIns
as well.