swift Build and install swift-testing in toolchains

As mentioned in the (now approved) A New Direction for Testing in Swift vision document, we're planning to include the swift-testing project in Swift toolchains soon. In preparation for that, this adds swift-testing to the update-checkout script, to its main branch scheme. This PR does not introduce any changes to the build process.

Jun 20 '24 18:06 stmontgomery

@swift-ci please smoke test

Jun 20 '24 18:06 stmontgomery

The swift-testing repo hasn't moved to swiftlang yet. Does that affect this PR?

Jun 21 '24 01:06 grynspan

The swift-testing repo hasn't moved to swiftlang yet. Does that affect this PR?

Right now, this PR is still using the current /apple organization for swift-testing. We'll want to ensure that at the point we merge this PR, it's using whatever the correct organization is at that time. But that said, the old URLs should redirect so it should be safe regardless.

Jun 21 '24 02:06 stmontgomery

Please test with following pull request: https://github.com/apple/swift-testing/pull/531

@swift-ci Please Build Toolchain macOS Platform

Jul 19 '24 02:07 stmontgomery

Please test with following pull request: https://github.com/apple/swift-testing/pull/531

@swift-ci Please Build Toolchain Linux Platform

Jul 19 '24 02:07 stmontgomery

Linux failure is in Foundation, not Swift Testing.

Jul 19 '24 12:07 grynspan

The Linux failure should be resolved in https://github.com/apple/swift-foundation/pull/748

Jul 19 '24 14:07 stmontgomery

Please test with following pull request: https://github.com/apple/swift-testing/pull/531

@swift-ci Please Build Toolchain Linux Platform

Jul 19 '24 14:07 stmontgomery

Closing on @stmontgomery's behalf as @rintaro has superseded it with #75515.

Aug 07 '24 19:08 grynspan