Shim package:test to avoid matcher issues (#20602)

* Upgrade everything except matcher.
* Roll matcher (and test)
* Adjust tests that depend on flutter:test directly to depend on a shim
* Require use of package:test shim and remove other references to package:test

dev/missing_dependency_tests/trivial_test.dart

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:test/test.dart';
+import 'package:test/test.dart' hide TypeMatcher, isInstanceOf;
 
 void main() {
   test('Trivial test', () {