[Compat] use _ENV.arg in lua instead of _G.arg

Haxe is a useful language for programming lua with stronger types, however, I have run into the issue that some lua "os"'s can't run haxe programs that utilize arguments. This is because haxe uses _G.arg, while these "os" believe arguments are local to a program's _ENV not _G. This specifically affects the minecraft mod ComputerCraft and means adding an extra build step to haxe programs that adds `_G.arg = _ENV.arg` at the start of every file.

Theoretically, this won't affect haxe programs since they usually run in a single lua file, so the _ENV and _G serve the same purpose.

Lua cli supports `_G.arg`, `_ENV.arg`, and `{ ... }`