Update the signature of DDS launcher callback. (flutter#154949)

Following https://dart-review.googlesource.com/c/sdk/+/383901

Author: chingjun

packages/flutter_tools/lib/src/base/dds.dart

@@ -28,7 +28,7 @@ typedef DDSLauncherCallback = Future<DartDevelopmentServiceLauncher> Function({
   bool enableServicePortFallback,
   List<String> cachedUserTags,
   String? dartExecutable,
-  Uri? google3WorkspaceRoot,
+  String? google3WorkspaceRoot,
 });
 
 // TODO(fujino): This should be direct injected, rather than mutable global state.
@@ -91,9 +91,7 @@ class DartDevelopmentService with DartDevelopmentServiceLocalOperationsMixin {
             ? const <String>['AppStartUp']
             : const <String>[],
         devToolsServerAddress: devToolsServerAddress,
-        google3WorkspaceRoot: google3WorkspaceRoot != null
-            ? Uri.parse(google3WorkspaceRoot)
-            : null,
+        google3WorkspaceRoot: google3WorkspaceRoot,
         dartExecutable: globals.artifacts!.getArtifactPath(
           Artifact.engineDartBinary,
         ),

packages/flutter_tools/test/general.shard/flutter_tester_device_test.dart

@@ -277,7 +277,7 @@ void main() {
         bool enableServicePortFallback = false,
         List<String> cachedUserTags = const <String>[],
         String? dartExecutable,
-        Uri? google3WorkspaceRoot,
+        String? google3WorkspaceRoot,
       }) async {
         return FakeDartDevelopmentServiceLauncher(uri: Uri.parse('http://localhost:1234'));
       };

packages/flutter_tools/test/general.shard/resident_runner_test.dart

@@ -1947,7 +1947,7 @@ flutter:
       bool enableServicePortFallback = false,
       List<String> cachedUserTags = const <String>[],
       String? dartExecutable,
-      Uri? google3WorkspaceRoot,
+      String? google3WorkspaceRoot,
     }) {
       throw DartDevelopmentServiceException.existingDdsInstance(
         'Existing DDS at http://localhost/existingDdsInMessage.',
@@ -1996,7 +1996,7 @@ flutter:
         bool enableServicePortFallback = false,
         List<String> cachedUserTags = const <String>[],
         String? dartExecutable,
-        Uri? google3WorkspaceRoot,
+        String? google3WorkspaceRoot,
       }) async {
       expect(remoteVmServiceUri, Uri(scheme: 'foo', host: 'bar'));
       expect(enableAuthCodes, isFalse);
@@ -2043,7 +2043,7 @@ flutter:
         bool enableServicePortFallback = false,
         List<String> cachedUserTags = const <String>[],
         String? dartExecutable,
-        Uri? google3WorkspaceRoot,
+        String? google3WorkspaceRoot,
       }) {
       expect(remoteVmServiceUri, Uri(scheme: 'foo', host: 'bar'));
       expect(enableAuthCodes, isTrue);