This reverts commit 2a113165.

* 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

No code changes, just comments: I spell-checked all the comments in the repo.

* implicit-casts:false on flutter_tools/lib

* address review comments

* use castStringKeyedMap

* introduce {bool,string,strings}Arg

* fix ci

* Generate projects using the new Android embedding

* Add comment about usesNewEmbedding:true

* Feedback

* Rework way to detect new embedding in new apps

This reverts commit 96482eeb.

Originally we wanted to cast as wide of a net and make the warning as
prominent as possible. Recently we've received feedback that the false
positives are more harmful than not, so downgrading the loud message to
a single line warning.