BUG: DataFrame.iloc.setitem with IntegerArray values
```
arr = pd.array([4, 5, 6])
df = pd.DataFrame(np.arange(3))

>>> df.iloc[:2] = arr[:2]
ValueError: could not broadcast input array from shape (2) into shape (2,1)

>>> df.iloc[:2] = arr[:2].to_numpy()  # <-- works fine
```

This bug would not occur with 2D EAs.