test: don't use --max-stack-size=0

--max-stack-size was removed in 3a87b31, use --stack-size instead.
What's more, a zero length stack will likely crash the process.
src: clean up CLI argument parser

* Exit with an error message when the option is not a node or V8 option.

* Remove the option_end_index global.  Needs to happen anyway for
  the multi-context work, might as well land it in master now.

* Add a smidgen of const-correctness.

* Pay off a few years of accrued technical debt.