* update packages

* implement

* remove trailing spaces

* Revert "remove trailing spaces"

This reverts commit d3bffbef57d142a4a5d98dea4c3e9b6db856c9bb.

* Revert "implement"

This reverts commit 6b6172a827c84985c5fe09e676096878fba43306.

* Update color scheme seed generation to use color utils package

Makes the android_semantics_testing test not fail for newer versions of Talkback.

Also, since the test now depends on pub_semver, upgraded the pubspec files.

The only substantive changes in the PR are in dev/integration_tests/android_semantics_testing/test_driver/main_test.dart

This adds a smoke test for every single API example. It also fixes 17 tests that had bugs in them, or were otherwise broken, and even fixes one actual bug in the framework, and one limitation in the framework.

The bug in the framework is that NetworkImage's _loadAsync method had await response.drain<List<int>>();, but if the response is null, it will throw a cryptic exception saying that Null can't be assigned to List<int>. The fix was just to use await response.drain<void>(); instead.

The limitation is that RelativePositionedTransition takes an Animation<Rect> rect parameter, and if you want to use a RectTween with it, the value emitted there is Rect?, and one of the examples was just casting from Animation<Rect> to Animation<Rect?>, which is invalid, so I modified RelativePositionedTransition to take a Rect? and just use Rect.zero if the rect is null.

- Update dwds and and the rest of the packages

Closes: https://github.com/flutter/flutter/issues/87100

* [web] move e2e tests from flutter/engine to flutter/flutter
* flutter update-packages --force-upgrade

* Add 'v' hotkey to open DevTools in the browser

* update pinned null safety deps

* run update-packages

* add http dep to devicelab package

* rerun update-packages