[SPARK-3836] [REPL] Spark REPL optionally propagate internal exceptions

Optionally have the repl throw exceptions generated by interpreted code, instead of swallowing the exception and returning it as text output. This is useful when embedding the repl, otherwise it's not possible to know when user code threw an exception.
```
  class SparkIMain(
      initialSettings: Settings,
      val out: JPrintWriter,
      propagateExceptions: Boolean = false)
    extends SparkImports with Logging { imain =>
```

Is that right?