samples(storagecontrol): add delete folder recursive sample

[nidhiii-27]

This PR adds the SDK sample and tests for the hierarchical namespace recursive delete feature, resolving b/521168740.

[snippet-bot]

Here is the summary of changes.

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• apis/Google.Cloud.Storage.Control.V2/Google.Cloud.Storage.Control.V2.Snippets/DeleteFolderRecursiveSample.cs:24, tag storage_control_delete_folder_recursive

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[gemini-code-assist]

Code Review

This pull request introduces a new sample and corresponding test for recursively deleting folders using the StorageControlClient. The review feedback suggests improving the sample by using the strongly-typed FolderName class instead of manual string formatting, and enhancing the test assertions to verify the exception message in addition to the status code.

[gemini-code-assist]

To align with the project's use of strongly-typed resource names (like BucketName), consider using FolderName instead of manually formatting the resource name string. This reduces the risk of formatting errors and makes the code cleaner.

            FolderName folderResourceName = FolderName.FromProjectBucketFolder("_", bucketName, folderName);

            storageControlClient.DeleteFolderRecursive(folderResourceName).PollUntilCompleted();

[gemini-code-assist]

According to the repository's general rules, when asserting that an exception is thrown in a test, we should also assert on the exception message to ensure the correct exception is being propagated.

                var ex = Assert.Throws<Grpc.Core.RpcException>(() => 
                    storageControlClient.GetFolder(new GetFolderRequest { Name = folder.Name }));
                Assert.Equal(Grpc.Core.StatusCode.NotFound, ex.StatusCode);
                Assert.Contains("not found", ex.Message, StringComparison.OrdinalIgnoreCase);

References

1. When asserting that an exception is thrown in a test, also assert on the exception message to ensure the correct exception is being propagated.

[github-actions]

Pull request diff results
Finding changes in Google.Cloud.Storage.Control.V2...
Comparing old and new versions (by source)
Diff level: Identical

Comparing with previous NuGet package
Checking compatibility for Google.Cloud.Storage.Control.V2 version 1.8.0
Differences from 1.8.0
Diff level: Identical

Finished comparisons for Google.Cloud.Storage.Control.V2

[amanda-tarafa]

The project where you have added these samples contains generated code only. It will be deleted and re-generated the next time the API changes.

Handwritten simples go in https://github.com/GoogleCloudPlatform/dotnet-docs-samples.

[amanda-tarafa]

I will be closing this PR now, because it cannot be merged on this repo. Thanks.