[CQ] migrate FlutterStudioStartupActivity to a project activity (flutter#8211)

The model for this change was set with
flutter#8200 and ties up our
migration off of the deprecated `StartupActivity` in favor of project
activities, leveraging IntelliJ's embrace of Kotlin coroutines for
improved startup performance.

Fixes: flutter#8100



---

- [x] I’ve reviewed the contributor guide and applied the relevant
portions to this PR.

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  <summary>Contribution guidelines:</summary><br>

- See our [contributor
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Author: pq

flutter-studio/src/io/flutter/FlutterStudioStartupActivity.java

@@ -7,7 +7,6 @@
 
 import com.intellij.openapi.application.ReadAction;
 import com.intellij.openapi.project.Project;
-import com.intellij.openapi.startup.StartupActivity;
 import com.intellij.util.concurrency.AppExecutorUtil;
 import io.flutter.android.AndroidModuleLibraryManager;
 import io.flutter.dart.FlutterDartAnalysisServer;
@@ -17,7 +16,7 @@
 import io.flutter.utils.GradleUtils;
 import org.jetbrains.annotations.NotNull;
 
-public class FlutterStudioStartupActivity implements StartupActivity {
+public class FlutterStudioStartupActivity extends FlutterProjectActivity {
   private static Void doNonBlockingStartup(@NotNull Project project) {
     if (AndroidUtils.isAndroidProject(project)) {
       GradleUtils.addGradleListeners(project);
@@ -39,7 +38,7 @@ private static Void doNonBlockingStartup(@NotNull Project project) {
   }
 
   @Override
-  public void runActivity(@NotNull Project project) {
+  public void executeProjectStartup(@NotNull Project project) {
     ReadAction.nonBlocking(() -> doNonBlockingStartup(project)).expireWith(FlutterDartAnalysisServer.getInstance(project))
       .submit(AppExecutorUtil.getAppExecutorService());
   }