* Revert "Include a directory with Flutter assets (#12944)"

This reverts commit 3af6b9cb.

* Revert "Upgrade project.pbxproj to include flutter_assets (#13011)"

This reverts commit 08128cb2.

* Revert "Upgrade complex_layout project.pbxproj to include flutter_assets (#13544)"

This reverts commit 35f1a041.

* mark complex_layout_ios__start_up as flaky

* update APK path in devicelab tests

* add missing transitive dependency on archive

* use path used by flutter tools

**This PR contains a breaking API change:**
`SemanticsConfiguration.addAction()` has been removed and replaces by action-specific setters (`onTap`, `onLongPress`, etc.) to take care of the fact that some action handlers (those, who take arguments) have different signatures.

Increase coverage collection timeout to 2 minutes. Leafy is hitting the limits of the previous timeout of 30 seconds for tests that touch a lot of code in the app. (#13527)

Add more tests, fix docs, fix painting bugs...

Fixes https://github.com/flutter/flutter/issues/12902

Add test for interim state of the animation to make sure we are transitioning the border color the right way. (#13499)

Includes:
flutter/engine#4425

Updating SDK and package versions now that alpha has been rolled to 0.0.20

Includes:
flutter/engine#4442
flutter/engine#4445
flutter/engine#4444
flutter/engine#4448 (reverts flutter/engine#4444)
flutter/engine#4447

We thought it would be OK to call the create command offline-only, but it turns out that isn't a great idea because not all of the create template dependencies are cached by running flutter_tool.

This PR makes it go online by default when running pub get after creating a project, and adds an "--offline" flag to the create command so that offline users can use it offline if their cache is warm.

See https://github.com/flutter/flutter/issues/11907 and https://github.com/flutter/engine/pull/4411

* Expose textAlign on TextFormField

Fixes #11404

* Added name to AUTHORS

* Added a test for TextFormWidget's textAlign

* Fix for incorrect transparent -> DividerColor animation for ExpansionTile

* Add comments and tests. Fix background color too.

* Fix analyzer warnings

Includes:
flutter/engine#4429
flutter/engine#4415
flutter/engine#4431
flutter/engine#4432
flutter/engine#4401
flutter/engine#4434
flutter/engine#4435
flutter/engine#4436

Removes bottom padding from the child AppBar in SliverAppBar. Scaffold
already does this for its own app bars, but sliver app bars in the body
should also apply the bottom padding removal.

Fixes flutter/flutter#13458

...instead of the engine.

This removes the FLUTTER_TEST_ARGS environment variable handling.

In order to allow offline usage of the create command we need to be able to tell pub not to try and contact the server to see if new versions are available. Since all the versions that create could want are pinned, it shouldn't need to check for new versions.

Also:

* Remove find.byIcon since it's identical to find.icon. (I sent mail to flutter-dev about this.)

* Fix IconData's operator== and hashCode, which had not been updated when we added fields.

* Add the byTooltip finder to the list of suggested finders.

* Make the suggested Key finder prettier.

* make time picker accessible

* use new CustomPaint a11y API

* flutter_localizations tests; use bigger distance delta

* fix am/pm control; selected values

* fix translations; remove @mustCallSuper in describeSemanticsConfiguration

* exclude AM/PM announcement from iOS as on iOS the label is read back automatically