Fix name property issue in SlotConfigNames resource in Azure.Provisioning.AppService

[ArcturusZhang]

Fixes #54675

[Copilot]

Pull request overview

This PR fixes the Name property issue in the SlotConfigNames resource by adding a default value for the Name property. The fix follows a similar pattern used for SiteAuthSettingsV2, where the Name property is configured with a default value generator.

• Added customization in the generator specification to make SlotConfigNames Name property generate a default value and hide accessors
• Implemented a partial class to provide the default Name value of "slotConfigNames"
• Updated the generated code to use the default value instead of treating Name as an output-only property

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

File	Description
sdk/provisioning/Generator/src/Specifications/AppServiceSpecification.cs	Added customization for SlotConfigNamesResource Name property to generate default value, hide accessors, and make it not read-only
sdk/provisioning/Azure.Provisioning.AppService/src/SlotConfigNames.cs	New partial class implementation providing a public Name getter and default value method returning "slotConfigNames"
sdk/provisioning/Azure.Provisioning.AppService/src/Generated/SlotConfigNames.cs	Removed the public Name property declaration (moved to partial class) and changed the property definition from output-only to use the default value
sdk/provisioning/Azure.Provisioning.AppService/CHANGELOG.md	Added changelog entry documenting the fix for issue #54675

[Copilot]

The public Name property getter is being exposed in the partial class, which appears inconsistent with the specification customization that sets HideAccessors=true. The SiteAuthSettingsV2 resource, which uses the same pattern, doesn't override the Name property with a public getter in its partial class. If the intention is to hide the setter while keeping the getter public, this pattern deviates from SiteAuthSettingsV2 and should be documented or reconsidered for consistency.

Suggested change

	public BicepValue<string> Name
	internal BicepValue<string> Name