[Aspire extension] Phase 3: Implement microsoft.azd.aspire providers

[vhvb1989]

Parent epic: #9479

Depends on the Aspire CLI contract spike and extension-driven detection support.

Objective

Create the first-party microsoft.azd.aspire extension and its aggregate Aspire application providers.

Extension capabilities

• Application detection/initialization provider.
• aspire service-target provider.
• aspire provisioning provider.
• Framework provider only where it adds value; language must remain optional.

Scope

• Discover and validate AppHosts using the Aspire CLI.
• Validate and report Aspire CLI installation/version requirements.
• Model the complete Aspire application as one aggregate azd service.
• Run Aspire publish/deployment operations and stream progress through azd.
• Translate Aspire failures into structured extension errors.
• Return service, deployment, resource, dashboard, and endpoint artifacts.
• Integrate azd environment values, AppHost parameters, and cancellation.
• Register providers consistently with extension.yaml and extension registry metadata.
• Add cross-platform packaging and signed first-party release support.

Non-goals

• Reproduce the built-in importer's synthetic child services.
• Reimplement Aspire's internal language or AppHost protocols.
• Remove the existing built-in implementation.

Exit criteria

• The extension can detect and run an end-to-end C# Aspire scenario through azd.
• Provider registration, lifecycle, errors, artifacts, and cancellation behave like other first-party extensions.