[packages] Migrate all iOS example apps in flutter/packages to UIScene

[Zubii12]

Migrate all iOS example apps in flutter/packages to UIScene lifecycle

Fixes flutter/flutter#188521

Pre-Review Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
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• 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.

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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 migrates the iOS examples of multiple packages to use UIScene and FlutterImplicitEngineDelegate, updating their AppDelegate and Info.plist configurations and bumping package versions. Review feedback highlights that the <key>UIApplicationSceneManifest</key> is missing before the <dict> element in the Info.plist files for extension_google_sign_in_as_googleapis_auth, file_selector, and file_selector_ios, which results in malformed plist files. Additionally, the Google Maps API key initialization was accidentally removed from the AppDelegate.swift of the google_maps_flutter example and needs to be restored.