* 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
* 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
