BUG: NaT comparison with numpy array doesn't work element-wise
I noticed the following behaviour:

```
In [43]: np.array([1, 2, 3]) == pd.Timedelta("1 days")
Out[43]: array([False, False, False])

In [44]: np.array([1, 2, 3]) == pd.Timedelta("nat")
Out[44]: False
```

@jbrockmendel do you know if this is something we control? (it's similar as the numeric/string comparison with numpy, but here the scalar is one defined by pandas)