`aspire start --format json` injects human readable messages

```shell
❯ aspire start --format json
🛑 Stopping previous instance (AppHost PID: 85610, CLI PID: 85605)
✔ Running instance stopped successfully.
{
"appHostPath": "/Users/sebastienros/tmp/aspire-app1/apphost.ts",
"appHostPid": 85707,
"cliPid": 85703,
"dashboardUrl": "https://localhost:17299/login?t=2f21864884251ab3d16c492e138cbc0b",
"logFile": "/Users/sebastienros/.aspire/logs/cli_20260403T144810200_detach-child_26500b6f7bd640fe8935fb200e692d22.log"
}
```

This should only emit JSON

Furthermore, `aspire stop` doesn't support `--format json`

```shell
❯ aspire stop --format json

Unrecognized command or argument '--format'.
Unrecognized command or argument 'json'.
```

but it might emit useful information to format, like start does

```
❯ aspire stop --non-interactive
Scanning for running apphosts...
📦 Found running AppHost: apphost.ts
🛑 Sending stop signal...
Stopping Aspire apphost...

✔ Apphost stopped successfully.
```