Feat. adding ext that returns change_time

[juliusl]

Addresses #112327

[rustbot]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @m-ou-se (or someone else) soon.

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[bors]

☔ The latest upstream changes (presumably #117285) made this pull request unmergeable. Please resolve the merge conflicts.

[m-ou-se]

This looks reasonable. Can you open a tracking issue for this and use that in the #[unstable] attribute for this new method? Thanks!

[rustbot]

There are merge commits (commits with multiple parents) in your changes. We have a no merge policy so these commits will need to be removed for this pull request to be merged.

You can start a rebase with the following commands:

$ # rebase
$ git rebase -i master
$ # delete any merge commits in the editor that appears
$ git push --force-with-lease

The following commits are merge commits:

• 073b87d

[juliusl]

@m-ou-se sorry for the git churning, created the tracking issue: #121478 and added the unstable attribute

[JohnCSimon]

@juliusl
Triage: Looks like this should have been placed back into review state
@rustbot ready