[various] Remove CocoaPods from examples

[stuartmorgan-g]

For almost all projects in the repository, this does the steps recommended by the warning when building with Swift Package Manager enabled (for both ios/ and macos/, wherever they are present):

• Runs pod deintigrate
• Deletes Podfile
• Removes the CocoaPod xcconfig references in the Flutter Debug and Release xcconfigs.

When running without Swift Package Manager enabled, flutter will automatically re-add this integration, so this won't break anyone running these examples on stable. However, we are no longer expecting this to be a common workflow (CI no longer builds these apps in non-SwiftPM mode, and regular flutter/package contributors are likely to be on master where SwiftPM is on by default now), so it's no longer useful to have the integration checked in.

The only packages that have not had Pod integration removed are:

• google_maps_flutter_ios because it doesn't (and can't) support Swift Package Manager.
• google_maps_flutter because it depends on google_maps_flutter_ios as the default implementation.

This also removes the precache steps from ios_build_all_packages and macos_build_all_packages. Because that step runs per package, it was doing a lot of caching of native code that was package-scoped, and thus wouldn't be used by the all-packages app, and in the current configuration isn't even the right kind of dependency (it will fetch SwiftPM deps, but the all-packages app uses CocoaPods still to cover that mode).

Follow-up to flutter/flutter#172427

Pre-Review Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the AI contribution guidelines and understand my responsibilities, or I am not using AI tools.
• I read the Tree Hygiene page, which explains my responsibilities.
• I read and followed the relevant style guides and ran the auto-formatter.
• I signed the CLA.
• The title of the PR starts with the name of the package surrounded by square brackets, e.g. [shared_preferences]
• I linked to at least one issue that this PR fixes in the description above.
• I followed the version and CHANGELOG instructions, using semantic versioning and the repository CHANGELOG style, or I have commented below to indicate which documented exception this PR falls under¹.
• I updated/added any relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or I have commented below to indicate which test exemption this PR falls under¹.
• All existing and new tests are passing.

Footnotes

1. Regular contributors who have demonstrated familiarity with the repository guidelines only need to comment if the PR is not auto-exempted by repo tooling. ↩ ↩²

[gemini-code-assist]

Code Review

This pull request removes CocoaPods integration from numerous example applications across various packages. The changes include the deletion of Podfiles, removal of CocoaPods-related includes from .xcconfig files, and updates to Xcode project files (.pbxproj) to eliminate all references to CocoaPods build phases, frameworks, and configurations. In some cases, Swift Package Manager dependencies are introduced through new Package.resolved files, reflecting a migration in dependency management.