Check node version manually on startup

[hdgarrood]

The purescript npm package currently has an engines constraint of >= 10.16.0, but this does not appear to be sufficient to stop people getting confused when the installer fails on older node versions, see e.g. purescript/purescript#3677. I think this is because npm only warns on an unsatisfied engines constraint by default rather than erroring.

We can make these failures easier to understand (and also not reliant on details of the particular npm client in use) by checking for them manually in this package and generating the appropriate errors ourselves.