[flutter_tools] disable source maps by default for release builds, enable for run and with command line arg (#67331)

Disables source map production by default for build web. For web builds performed as a part of flutter run --release, enable the source maps, or allow force enabling with --source-maps command line flag.

fixes #67328

Fix run release/profile modes generating a full service worker.

In web debug mode, infer sound null safety by default. When sound null safety is enabled, provide a separate dill and precompiled Dart SDK. Release builds do not need this setting since we run dart2js from source.

Fixes #59873

Instead of targets/dart.dart -> targets/common.dart

Also combines experiments into extraGenSnapshot/ExtraFrontEndOptions. Allows providing --no-sound-null-safety to allow out of order migration and running.

This reverts commit b8bd09db.

* Reland: [flutter_tool] Where possible, catch only subtypes of Exception

* Add armv7f to getIOSArchForName

This reverts commit aed96199.

Revert "[flutter_tools] Allow providing dart-defines to Android, iOS, macOS builds (#51714)" (#52041)

This reverts commit ee60eeea.

* [flutter_tools] supports tree-shake-icons for web builds

* Update compile.dart

* fix icon_tree_shaker

This reverts commit 57c6721c.

This reverts commit 9de7787f.

This reverts commit f1cd47ef.

* 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.