BUG: Identity checking NA in `map` is incorrect

```python
In [2]: pd.Series([pd.NA], dtype="Int64").map(lambda x: 1 if x is pd.NA else 2)
Out[2]: 
0    2
dtype: int64
```

In pandas 2.1

```python
In [2]: pd.Series([pd.NA], dtype="Int64").map(lambda x: 1 if x is pd.NA  else 2)
Out[2]: 
0    1
```

This is probably because we call `to_numpy` before going through `map_array`