Fix GH-17935: Add delayed separation in ArrayObject

[alexandre-daubois]

Fix #17935

[ndossche]

This is conceptually the same fix Ilija proposed a while ago, but this just fixes a symptom rather than the underlying problem. Please see my messages in the thread #17942

[alexandre-daubois]

@ndossche I tried to implement thanks to your info on the other PR. Friendly ping @iluuu1994 as you worked on the linked PR/issue

[Girgias]

I will be honest in that I don't think I can review this, I don't really understand the whole reference counting logic that got introduced other than it fixed some bugs reported by one or two people when they were playing around with ArrayObject. I also don't know if a lot of the implementation of this class could be simplified drastically when we finally get rid of using objects as backing "arrays" as it seems that a lot of internal behaviour tracking is caused by that.