fix(api): make Tracing.group return Disposable

Tracing.group() now returns a Disposable that calls groupEnd() on
dispose, enabling `await using` pattern for automatic group cleanup.

Author: pavelfeldman

docs/src/api/class-tracing.md

@@ -305,6 +305,7 @@ To specify the final trace zip file name, you need to pass `path` option to
 
 ## async method: Tracing.group
 * since: v1.49
+- returns: <[Disposable]>
 
 :::caution
 Use `test.step` instead when available.

packages/playwright-client/types/types.d.ts

@@ -21957,7 +21957,7 @@ export interface Tracing {
 
       column?: number;
     };
-  }): Promise<void>;
+  }): Promise<Disposable>;
 
   /**
    * Closes the last group created by

packages/playwright-core/src/client/tracing.ts

@@ -16,6 +16,7 @@
 
 import { Artifact } from './artifact';
 import { ChannelOwner } from './channelOwner';
+import { DisposableStub } from './disposable';
 
 import type * as api from '../../types/types';
 import type * as channels from '@protocol/channels';
@@ -62,6 +63,7 @@ export class Tracing extends ChannelOwner<channels.TracingChannel> implements ap
     if (options.location)
       this._additionalSources.add(options.location.file);
     await this._channel.tracingGroup({ name, location: options.location });
+    return new DisposableStub(() => this.groupEnd());
   }
 
   async groupEnd() {

packages/playwright-core/types/types.d.ts

@@ -21957,7 +21957,7 @@ export interface Tracing {
 
       column?: number;
     };
-  }): Promise<void>;
+  }): Promise<Disposable>;
 
   /**
    * Closes the last group created by