Rename ConfigureHostApplicationBuilder to ConfigureWebApplicationBuilder

[Copilot]

API-approved rename of ConfigureHostApplicationBuilder → ConfigureWebApplicationBuilder on WebApplicationFactory<TEntryPoint> to avoid confusion with Host.CreateApplicationBuilder/Host.CreateDefaultBuilder scenarios.

Description

• WebApplicationFactory.cs: Renamed protected virtual method and private reflection helper; updated all call sites and nameof references
• Resources.resx: Renamed resource key ConfigureHostApplicationBuilderNotSupported → ConfigureWebApplicationBuilderNotSupported; updated error message text
• PublicAPI.Unshipped.txt: Updated public API surface entry
• TestingInfrastructureInheritanceTests.cs: Updated test fixture class and override references

-protected virtual void ConfigureHostApplicationBuilder(IHostApplicationBuilder hostApplicationBuilder);
+protected virtual void ConfigureWebApplicationBuilder(IHostApplicationBuilder hostApplicationBuilder);

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[Copilot]

Pull request overview

Renames the WebApplicationFactory<TEntryPoint> protected customization hook from ConfigureHostApplicationBuilder to ConfigureWebApplicationBuilder to better align with WebApplicationBuilder terminology and avoid confusion with generic host builder APIs.

Changes:

• Renamed the protected virtual method to ConfigureWebApplicationBuilder and updated the internal override-detection helper and call sites.
• Updated the corresponding resource key/message used for the unsupported-override exception.
• Updated functional tests and PublicAPI tracking to reflect the rename.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
src/Mvc/test/Mvc.FunctionalTests/TestingInfrastructureInheritanceTests.cs	Updates test factory type/override usage and asserted exception message to the new method name.
src/Mvc/Mvc.Testing/src/WebApplicationFactory.cs	Renames the customization hook and override detection, and updates exception resource usage accordingly.
src/Mvc/Mvc.Testing/src/Resources.resx	Renames the resource key and updates message text to reference ConfigureWebApplicationBuilder.
src/Mvc/Mvc.Testing/src/PublicAPI.Unshipped.txt	Updates the unshipped public API entry for the renamed protected virtual method.