feat: add global compiler arguments

## Summary - allow specifying `global_arg` in project files so flags apply to dependencies - treat `32bit` directive as shorthand for `global_arg -m32` ## Testing - `g++ -std=c++20 -I Sun/vendor/Soup -pthread -c Sun/sun.cpp -o /tmp/sun.o && echo 'Compilation succeeded'` ------ https://chatgpt.com/codex/tasks/task_e_68b30aaee004832596df84a13f2de8b7