Introduce stopAfterWithResult

[edsko]

Before submitting your PR, check that you've:

• Bumped the version number
• Documented new APIs with Haddock markup
• Added @since declarations to the Haddock

After submitting your PR:

• Update the Changelog.md file with a link to your PR
• Check that CI passes (or if it fails, for reasons unrelated to your change, like CI timeouts)

[edsko]

CI failure seems unrelated to this PR..? 🤔

[Vlix]

PR looks fine in principle. Though it might have to be a major version bump, since the API for KilledByThreadManager has changed. (And there's an extra constraint on stopAfter)

Also, the CI failures are indeed because of this PR. threadLabel is only available from base-4.18 onward. So we'll need something like the following to make it build on older GHCs.

#if MIN_VERSION_base(4,18,0)
    mLabel <- threadLabel tid
#else
    let mLabel = Nothing
#endif

(and of course some CPP at the import of threadLabel)

[edsko]

Oh! I'm so sorry, this included changes that I didn't intend to include. Sincere apologies, I will roll those back and leave only stopAfterWithResult.

[edsko]

@Vlix Ok, I've force-pushed to the branch, leaving only stopAfterWithResult, which does not introduce any backwards incompatible changes. Apologies again, I clearly should not have submitted this PR at the end of a long working week 😅

[Vlix]

Apologies again, I clearly should not have submitted this PR at the end of a long working week 😅

Geen probleem, kan gebeuren 👍

---

Addition is short and to the point, passes all checks, I see nothing wrong with this.
I will probably merge and publish somewhere at the end of the week.

[edsko]

Dank je wel! :)