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.
* Update project.pbxproj files to say Flutter rather than Chromium
Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.
* Update the copyright notice checker to require a standard notice on all files
* Update copyrights on Dart files. (This was a mechanical commit.)
* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.
Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).
* Clean up the copyrights in non-Dart files. (Manual edits.)
Also, make sure templates don't have copyrights.
* Fix some more ORGANIZATIONNAMEs
