Editorial: allow [[AsyncEvaluationOrder]] to have any value when errored

[nicolo-ribaudo]

Fixes #3613 (comment).

[[AsyncEvaluationOrder]] is only use/used for non-yet evaluated modules.

• ~DONE~ was added to distinguish the "not an integer and never was" case an assertion (Editorial: Adjust invalid assertion about [[AsyncEvaluationOrder]] #3613 (comment)) from "not an integer anymore" case (before we would just transition back from an integer to UNSET, or from true to false when using booleans). The goal of that assertion was to assert that "when we start executing an async module, we never tried to execute it before": leaving [[AsyncEvaluationOrder]] as an integer still fulfills that goal.
• it is possible we can now leave [[AsyncEvaluationOrder]] as an integer forever also for non-error cases. Historically that was not possible because Evaluate() checked if the root module was still pending by checking that [[AsyncEvaluation]] was false (which, after the rewrite to [[AsyncEvaluationOrder]], would be equivalent to "[[AsyncEvaluationOrder]] is not an integer"), but now it's just checking that [[Status]] is EVALUATED.
  • This would be a follow up if we want to do it.

[github-actions]

The rendered spec for this PR is available as a single page at https://tc39.es/ecma262/pr/3787 and as multiple pages at https://tc39.es/ecma262/pr/3787/multipage .