Transfer more tests to shared test project (cfug#2161)

This PR transfers some download and header/options tests to the shared
test project and thus enabled them for the Http2 adapter.

### New Pull Request Checklist

- [ ] I have read the
[Documentation](https://pub.dev/documentation/dio/latest/)
- [ ] I have searched for a similar pull request in the
[project](https://github.com/cfug/dio/pulls) and found none
- [ ] I have updated this branch with the latest `main` branch to avoid
conflicts (via merge from master or rebase)
- [ ] I have added the required tests to prove the fix/feature I'm
adding
- [ ] I have updated the documentation (if necessary)
- [ ] I have run the tests without failures
- [ ] I have updated the `CHANGELOG.md` in the corresponding package

### Additional context and info (if any)

<!-- Provide more context and info about the PR. -->

.github/workflows/tests.yml

@@ -85,7 +85,7 @@ jobs:
         run: melos run httpbun:local
       - name: '[Verify step] Test Dart packages [VM]'
         run: melos run test:vm
-      - name: Use httpbun.com for VM/Flutter tests
+      - name: Use httpbun.com for Web/Flutter tests
         run: melos run httpbun:com
       - name: '[Verify step] Test Dart packages [Chrome]'
         run: melos run test:web:chrome

dio/dart_test.yaml

@@ -20,4 +20,4 @@ override_platforms:
       arguments: --headless
       executable:
         # https://github.com/dart-lang/test/pull/2195
-        mac_os: '/Applications/Firefox.app/Contents/MacOS/firefox'
+        mac_os: '/Applications/Firefox.app/Contents/MacOS/firefox'

dio/test/cancel_token_test.dart

@@ -1,5 +1,6 @@
 import 'package:dio/dio.dart';
 import 'package:dio/src/adapters/io_adapter.dart';
+import 'package:dio_test/util.dart';
 import 'package:mockito/mockito.dart';
 import 'package:test/test.dart';
 
@@ -60,16 +61,18 @@ void main() {
       for (final future in futures) {
         expectLater(
           future,
-          throwsA(
-            (error) =>
-                error is DioException &&
-                error.type == DioExceptionType.cancel &&
-                error.error == reason,
+          throwsDioException(
+            DioExceptionType.cancel,
+            matcher: isA<DioException>().having(
+              (e) => e.error,
+              'error',
+              reason,
+            ),
           ),
         );
       }
 
-      await Future.delayed(const Duration(milliseconds: 50));
+      await Future.delayed(const Duration(milliseconds: 100));
       token.cancel(reason);
 
       expect(requests, hasLength(2));