[Aspire extension] Phase 5: Add polyglot Aspire support

Parent epic: #9479

Depends on stable aggregate extension workflows.

## Objective

Support non-C# Aspire AppHosts through the Aspire CLI without adding language-specific runtime implementations to azd.

## Rollout

1. Establish C# parity as the reference implementation.
2. Add TypeScript/JavaScript AppHost coverage.
3. Add Python AppHost coverage.
4. Add Go, Java, Rust, and future languages as they reach an appropriate Aspire support level.

## Scope

- Use Aspire CLI discovery and execution for every language.
- Remove the current azd behavior that rejects detected polyglot AppHosts when the extension supports them.
- Follow Aspire's own experimental feature flags and support classifications.
- Add language-specific fixtures covering init, deployment, endpoints, errors, and CI/no-prompt use.
- Document required language runtimes and Aspire CLI versions.
- Ensure telemetry reports fixed normalized language values without inspecting customer content.

## Exit criteria

- TypeScript/JavaScript and Python AppHosts can use the supported azd workflow matrix.
- Experimental languages are explicitly gated and are not represented as more stable than upstream Aspire.
- New Aspire languages can generally be enabled through compatibility testing rather than new azd deployment code.