* Roll Flutter Engine from 67254d6e4b03 to 8d83b98c55b3
* Roll Dart SDK from 35a9facce191 to e517487c5679 (Dart 3.0) (#38105)
* Bump SDK versions.
* Bump Dart SDK version constraints
* Update shrine package to 2.0.1 (null safe version)
* Fix more tests.
* Include patches from Jason for min android sdk version
* Fix analyzer warning
Switch document generation to use the snippets package instead of the snippets code in the Flutter repo. In the process, some bugs in sample code analysis have been fixed, and I've fixed some more errors in the samples.
This will allow the snippets package to be developed separately from the Flutter repo, and reduce the code in the Flutter repo.
The snippets code is deleted in this PR.
I also converted some comments in the snippet templates to be regular comments instead of doc comments, because having a doc comment block before the imports causes the Dart import sorter to lose the comment. They should have been regular comments in the first place.
The snippets package resides in the assets-for-api-docs repo.
The sample analysis has also been converted to be run in parallel, and I've bumped the Dartdoc version to 1.0.2.
* 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
