add file_suffix method to std::path

[EvanCarroll]

This adds file_suffix as suggested in #86319. file_prefix was added in #85166.

I wanted the file_suffix to be everything that's NOT the file_prefix.

For foo.tar.gz, foo is the file_prefix. .tar.gz is the file_suffix.

[rust-highfive]

Hey! It looks like you've submitted a new PR for the library teams!

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[rust-highfive]

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

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[EvanCarroll]

I can write tests if this implementation is approved in #86319

[JohnCSimon]

Triage:
@EvanCarroll - I guess this is still waiting on #86319 ?

[bors]

☔ The latest upstream changes (presumably #102097) made this pull request unmergeable. Please resolve the merge conflicts.

[joshtriplett]

This seems fine to me as a companion to file_prefix.

Please do rebase and add tests.

[JohnCSimon]

This seems fine to me as a companion to file_prefix.

Please do rebase and add tests.

@EvanCarroll ☝️

[JohnCSimon]

@EvanCarroll

ping from triage - can you post your status on this PR? There hasn't been an update in a few months. Thanks!

FYI: when a PR is ready for review, send a message containing
@rustbot ready to switch to S-waiting-on-review so the PR is in the reviewer's backlog.

[EvanCarroll]

Sorry, I forgot about this thanks for the ping I'll give it a go.

[JohnCSimon]

@EvanCarroll

Ping from triage: I'm closing this due to inactivity, Please reopen when you are ready to continue with this.
Note: if you are going to continue please open the PR BEFORE you push to it, else you won't be able to reopen - this is a quirk of github.
Thanks for your contribution.

@rustbot label: +S-inactive