Ensure WithHttpCommand adds HttpClientFactory

[DamianEdwards]

Description

Ensures that IHttpClientFactory is registered in the DistributedApplication DI container when WithHttpCommand is called.

Fixes #8270

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
• Did you add public API?
  • No
• Does the change make any security assumptions or guarantees?
  • No
• Does the change require an update in our Aspire docs?
  • No

[Copilot]

Pull Request Overview

This PR ensures that IHttpClientFactory is registered in the DI container when WithHttpCommand is invoked, enabling HTTP commands to function as expected. Key changes include:

• Adding a call to register IHttpClientFactory via AddHttpClient() in the WithHttpCommand extension.
• Introducing a new unit test to verify that the IHttpClientFactory is added to the service collection.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/Aspire.Hosting/ResourceBuilderExtensions.cs	Registers IHttpClientFactory in the DI container within WithHttpCommand
tests/Aspire.Hosting.Tests/WithHttpCommandTests.cs	Adds unit tests to validate the HTTP client factory registration