Enable UIScene Migration and update create templates

[vashworth]

Updates create templates for both iOS app and module to be migrated to UIScene. Can be tested with:

flutter create --platforms=ios my_app
flutter create --template module my_module

Module is integration tested in module_test_ios.

Also, enables the UIScene tool migration to be enabled by default.

Fixes #170293.
Fixes #177266.
Fixes #177265.
Fixes #167267.

Pre-launch Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I read the Tree Hygiene wiki page, which explains my responsibilities.
• I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
• I signed the CLA.
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is test-exempt.
• I followed the breaking change policy and added Data Driven Fixes where supported.
• All existing and new tests are passing.

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[gemini-code-assist]

Code Review

This pull request enables the UIScene migration by default and updates the iOS project templates to be compliant with the UIScene lifecycle. This includes adding SceneDelegate files, updating Info.plist with the UIApplicationSceneManifest, and moving plugin registration to the didInitializeImplicitFlutterEngine delegate method. The changes are applied consistently across app and module templates for both Swift and Objective-C. The integration tests have also been updated to reflect these changes. The implementation looks solid. I've only found a couple of minor style issues in the new Objective-C template files.

[gaaclarke]

reason for revert: causing failures in post submit tests

example: https://ci.chromium.org/ui/p/flutter/builders/prod/Mac_ios%20platform_channels_benchmarks_ios/24421/overview

[2025-11-17 09:10:06.660248] [STDOUT] [STDOUT] [   +7 ms] Checking for advertised Dart VM Services...
[2025-11-17 09:10:06.671607] [STDOUT] [STDOUT] [  +11 ms] #0      _NativeSocket.send (dart:io-patch/socket_patch.dart:1524:34)
[2025-11-17 09:10:06.671636] [STDOUT] [STDOUT]            #1      _RawDatagramSocket.send (dart:io-patch/socket_patch.dart:3043:15)
[2025-11-17 09:10:06.671643] [STDOUT] [STDOUT]            #2      MDnsClient.lookup (package:multicast_dns/multicast_dns.dart:227:22)
[2025-11-17 09:10:06.671648] [STDOUT] [STDOUT]            #3      MDnsVmServiceDiscovery._doPollingVmService (package:flutter_tools/src/mdns_discovery.dart:308:66)
[2025-11-17 09:10:06.671652] [STDOUT] [STDOUT]            <asynchronous suspension>
[2025-11-17 09:10:06.671656] [STDOUT] [STDOUT]            #4      MDnsVmServiceDiscovery._pollingVmService.<anonymous closure> (package:flutter_tools/src/mdns_discovery.dart:241:62)
[2025-11-17 09:10:06.671660] [STDOUT] [STDOUT]            <asynchronous suspension>
[2025-11-17 09:10:06.671663] [STDOUT] [STDOUT] 
[2025-11-17 09:10:06.675643] [STDERR] [STDERR] [        ] Flutter could not access the local network.
[2025-11-17 09:10:06.675692] [STDERR] [STDERR] 
[2025-11-17 09:10:06.675697] [STDERR] [STDERR]            Please ensure your IDE or terminal app has permission to access devices on the local network. This allows Flutter to connect to the Dart VM.
[2025-11-17 09:10:06.675821] [STDERR] [STDERR] 
[2025-11-17 09:10:06.675841] [STDERR] [STDERR]            You can grant this permission in System Settings > Privacy & Security > Local Network.
[2025-11-17 09:10:06.675848] [STDERR] [STDERR] 
[2025-11-17 09:10:06.675853] [STDERR] [STDERR]            SocketException: Send failed (OS Error: No route to host, errno = 65), address = 0.0.0.0, port = 5353
[2025-11-17 09:10:06.675858] [STDERR] [STDERR] 
[2025-11-17 09:10:06.675886] [STDOUT] [STDOUT] [        ] mDNS query failed. Checking for an interface with a ipv4 link local address.
[2025-11-17 09:10:06.675895] [STDOUT] [STDOUT] [        ] Found interface "en9":
[2025-11-17 09:10:06.675922] [STDOUT] [STDOUT] [        ] 	Bound address: "169.254.178.22" link local
[2025-11-17 09:10:06.675930] [STDOUT] [STDOUT] [        ] Found interface "en0":
[2025-11-17 09:10:06.675934] [STDOUT] [STDOUT] [        ] 	Bound address: "100.127.108.108" 
[2025-11-17 09:10:06.675949] [STDOUT] [STDOUT] [        ] An interface with an ipv4 link local address was found.
[2025-11-17 09:10:18.919302] [STDOUT] [STDOUT] [+12245 ms] VM Service URL on device: http://127.0.0.1:65053/YjYg2LtViS8=/