[chrfalch]

Summary:

The iOS CI jobs that build our test apps still use CocoaPods: RNTester, HelloWorld, and the template app that the Maestro end-to-end tests run. SwiftPM is becoming the default way to build React Native apps on iOS, so CI should build these apps with SwiftPM.

This PR changes those jobs to SwiftPM:

1. HelloWorld is converted to SwiftPM and checked in. Its Podfile, workspace and Ruby files are removed. yarn bootstrap ios and yarn build ios now use SwiftPM.
2. RNTester stays a CocoaPods project in git, so developers can still build React Native from source in it. CI converts it to SwiftPM before each build (spm scaffold, then spm add --deintegrate).
3. The RNTester app that the Maestro tests use keeps its artifact name, RNTesterApp-NewArch-{Debug,Release}, so the Maestro jobs do not change.
4. The template app for the Maestro tests is converted to SwiftPM in its build job.
5. A new action, setup-spm-artifacts, gives each job the prebuilt frameworks from the same CI run.
6. test_ios_rntester now blocks a merge. It replaces the blocking test_ios_spm_rntester job.
7. These jobs and workflows are removed: the Ruby 3.2 jobs, the dynamic-frameworks job, the use_frameworks matrix axis, and test-ios-spm-rntester.yml / test-ios-spm-helloworld.yml (the jobs above now cover them).

Things reviewers should know:

• After this PR, no CI job builds an app with CocoaPods. A separate PR will add a test for the CocoaPods opt-out.
• The check names change, for example test_ios_rntester (Debug, false) becomes test_ios_rntester (Debug). If branch protection lists the old names, it must be updated.
• The RNTester and HelloWorld unit-test targets are not built by any CI job today. They do not build after the SwiftPM conversion. A follow-up PR will fix them.

Changelog:

[INTERNAL] [CHANGED] - Build the iOS test apps with SwiftPM in CI

Test Plan:

Local, Xcode, iPhone simulator:

• RNTester, starting from the CocoaPods project in git, with the same commands as the CI action: spm scaffold, spm add --deintegrate, then xcodebuild -project RNTesterPods.xcodeproj -scheme RNTester. Debug and Release: BUILD SUCCEEDED. The embedded React.framework has the matching flavor (nm | grep getDebugProps: 81 symbols in Debug, 0 in Release).
• HelloWorld, from a clean checkout: yarn bootstrap ios && yarn build ios in private/helloworld: BUILD SUCCEEDED. yarn bundle ios: passes. Before this change, all three commands failed on the converted project ("No Podfile found").
• yarn flow-check: 0 errors. npx eslint --max-warnings 0 on the changed JavaScript files: clean.

Not run locally: the template-app job and test-ios-spm-newapp.yml. The CI run on this PR tests them.

[chrfalch]

@cipolleschi This PR changes the iOS CI jobs to build our test apps with SwiftPM instead of CocoaPods. SwiftPM becomes the default in 0.89, so CI should test that setup. The PR is ready for your review.

What changes:

• HelloWorld is checked in as a SwiftPM project.
• RNTester stays CocoaPods in git, so developers can still build from source. CI converts it to SwiftPM before each build.
• The template app for the Maestro tests is converted in its build job.
• CI is green on the current commit. All iOS jobs pass in Debug and Release.

Things that need your attention:

• Check names change. For example, test_ios_rntester (Debug, false) becomes test_ios_rntester (Debug). If branch protection lists the old names, it needs an update.
• test_ios_rntester now blocks a merge.
• After this PR, no CI job builds an app with CocoaPods. The CocoaPods opt-out landed in Let spm deinit take an app back to CocoaPods #59368. A follow-up PR adds a CI test that builds an app with that opt-out.
• The RNTester and HelloWorld unit-test targets do not build after the conversion. No CI job builds them today. A follow-up PR fixes them.