Allow `--heap-size-hint` option to be passed

This option is really useful for when the Julia garbage collector is doing a bad job. e.g., https://github.com/MilesCranmer/PySR/discussions/441, https://github.com/JuliaLang/julia/issues/50673, https://github.com/MilesCranmer/PySR/discussions/61.

All of these types of issues seem to be easily fixable if you just tell Julia to use a smaller size hint, so the GC works more aggressively. I find this option extremely useful so we should definitely add it.