[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

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[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.

[stuartmorgan-g]

I'll leave it to the iOS team to decide whether we want to keep all of these no-op overrides; generally we wouldn't have an override that did nothing but call super.

[Zubii12]

There are a few examples already migrated to the UIScene lifecycle, they all keep this no-op method.

Let me know if you want me to remove them.