testsuite: Fix and extend closure_size test

This was previously broken in several ways. This is fixed and it also now tests arrays. Unfortunately I was unable to find a way to continue testing PAP and FUN sizes; these simply depend too much upon the behavior of the simplifier.

I also tried to extend this to test non-empty arrays as well but unfortunately this was non-trivial as the array card size constant isn't readily available from haskell.

Fixes #16531 (closed).