Protected/Private `has` attributes should be omitted when `report`

[ypkang]

Describe the feature you'd like

Private has variables should be omitted when reported.

Examples

node Doc {
  has text: str = "This is a text".
  has:priv embedding: list[float];
}

d = Doc();
report d;

The reported data of node d should not include the private attribute embeddings.

[ypkang]

@amadolid I think this one is pretty straightforward. If you also agree this makes sense, you can go ahead and pick this up.