[VS Code] Complete AppHost run and resource debugging workflows

## Goal

Make AppHost launch and per-resource debugging in VS Code reliable, configurable, and discoverable across supported languages.

This is an area tracker under #19405.

## Exit criteria

- AppHost launch honors supported `launch.json` debugger settings.
- Missing language debugger dependencies produce actionable install guidance.
- Users can attach supported debuggers to eligible resources in an already-running AppHost.
- Per-language launch, attach, breakpoint, and teardown behavior has end-to-end coverage.
- Azure Functions and Java resources follow the supported resource-debugging lifecycle.
- Debug output is readable, correctly classified, and not duplicated.
- Hot-reload guidance respects the user's dismissal and configuration choices.

## Tracked work

- #19387
- #17845
- #18538
- #18957
- #19138
- #18047
- #19408
- #19544

## Scope

Reuse VS Code debugger extensions and Aspire resource metadata rather than implementing language-specific debuggers. Preserve `launch.json` as the advanced configuration surface while making supported launch and attach paths work from Aspire commands and the Aspire pane.