ENH: Vectorize iterrows

For instance

```python
df = pd.DataFrame({"A": [0 ,1], "B": [0, 2]})

res = []
for index, row in df.iterrows():
   res.append(row["A"])
```

should be converted to

```python
df = pd.DataFrame({"A": [0 ,1], "B": [0, 2]})

res = df["A"].tolist()
```
