Change the following in the `flutter create` templates.  I didn't make any auto-migrations for existing apps because none seem that critical:
1. Turn on `ASSETCATALOG_COMPILER_GENERATE_SWIFT_ASSET_SYMBOL_EXTENSIONS` in iOS and macOS.
1. Turn on `BuildIndependentTargetsInParallel` in macOS template.  https://github.com/flutter/flutter/pull/125827/files#r1181817619 
1. Turn on `DEAD_CODE_STRIPPING` in macOS template. 
1. Set `ENABLE_USER_SCRIPT_SANDBOXING=NO` in iOS and macOS template.  `flutter` scripts don't work with this on.  This might require a migration in the future to explicitly turn this one off. However at least for now if the setting isn't present it defaults to `NO`.

Add migration for `LastUpgradeVersion` so users won't see these validation issues in Xcode.

Run migrator on all the example apps.  A few aren't Flutter apps so I edited them in Xcode.

Fixes https://github.com/flutter/flutter/issues/140253
See also https://github.com/flutter/flutter/issues/125817 and https://github.com/flutter/flutter/pull/90304.

1. Add iOS and macOS migration to mark "last upgraded" Xcode version to 14.3 to prevent `Update to recommended settings` warning.
2. Update iOS and macOS templates to same.
3. Update iOS template to set `BuildIndependentTargetsInParallel` to YES as suggested.  I didn't add a migration for this since it seems like a minor optimization and I don't think it's worth a potentially botched/corrupted migration.
4. Run all example/integration test project to see migrator work.
5. Add some missing test projects to the build shard since I noticed they were missing and I had to build those manually outside `SHARD=build_tests`.

Fixes https://github.com/flutter/flutter/issues/125817
See https://github.com/flutter/flutter/pull/90304 for Xcode 13 example.

This reverts commit bfe9c598.

This reverts commit 31e33647.

This change updates the platform runners in the benchmarks subdir.

I've attempted to replace the entire group with new code as if the project were recreated with flutter create so that they don't become a Frankenstein of minor changes to make it work again, but just plain old generated code that can be replaced and updated in place.

This reverts commit df833986.