XFN Runner: Show STDOUT of failed composition function (exit code >= 1)

### What problem are you facing?

We've implemented a function similar to the example functions from [docs](https://docs.crossplane.io/master/concepts/composition-functions/#an-example-function). If this functions fails, it returns a exit code greater than 0 and prints the error message in STDOUT.

```
[..] "error": "cannot run Composition Function pipeline: cannot run function \"service-versioning\": cannot run container: rpc error: code = Unknown desc = exit status 1: xfn: error: spark.Command.Run(): OCI runtime error: exit status 1"
```

Currenty, I cannot debug a composition function that fails to execute. When the function in the OCI container fails, I see the exit code but no additional information printed in STDOUT.

### How could Crossplane help solve your problem?

Provide a way to see the STDOUT of functions that failed. That may be behind a flag/option like verbosity level/debug mode, etc.
Perhaps, also STDERR could be used, as it would be the more appropriate place for error messages.

En el issue no se menciona ningún archivo fuente ni ninguna prueba. Empieza por localizar la ruta de ejecución del contenedor OCI y reproduce una función de composición que termine con un estado distinto de cero mientras escribe en STDOUT; determina cómo debería exponerse la salida fallida, incluido si se gestiona STDERR, y añade cobertura que demuestre que el texto de diagnóstico es visible.

Escrito por el modelo de indexación a partir del texto del issue.