QCheck.0.90 migration

[jmid]

The QCheck.0.90 release revises the API, deprecating a number of previous bindings:
https://github.com/c-cube/qcheck/releases/tag/v0.90

With the help of https://github.com/v-gb/ocamlmig and the forthcoming annotations from c-cube/qcheck#398, I've been able to migrate to the new API without much effort.

In a subsequent pass, I then reviewed the changes:

• Here I discovered Lin.int_small would be translated to use nat_small (for a distribution-preserving mapping) which excludes negative numbers, and therefore changed it to instead use the new int_small including negative numbers. In effect this creates an API change of behavior.
• I also simplified some array combinators to use array_small.

Let's see if the changes causes the CI test suite to behave any different...

[jmid]

CI summary:

• Linux trunk debug failed with [ocaml5-issue] Assertion error on weak/lin_tests_hashset with trunk #572
• MinGW trunk failed with [ocaml5-issue] MinGW+MSVC 5.5.0+trunk may fail Lin Dynlink stress test with Domain with code 0xc0000374 #576

Out of 51 workflows 2 failed with genuine errors

[jmid]

CI summary for merge to main:

• Linux trunk debug failed with [ocaml5-issue] Assertion error on weak/lin_tests_hashset with trunk #572

Out of 52 workflows 1 failed with a genuine error