Draft: Strictify datatypes and state monads to reduce run-time memory

[basvandijk]

This sledgehammer approach is a quick experiment to see if we can reduce the 17GB memory usage of ic-ref when run inside the ic-ref-test and coverage jobs.

The right approach is to do a space profile and see what is being allocated and why. But I'm lazy so doing this first to see if it helps.

I'll close this draft PR if it doesn't help.