BUG: Unable to add np.timedelta64 + pd.Interval(pd.Timestamp, pd.Timestamp)
Note: this is currently _not_ a bug on master but will be after https://github.com/pandas-dev/pandas/pull/35938, which reverts a change that caused other regressions.

```python
import numpy as np
import pandas as pd

delta = np.timedelta64(0)
interval = pd.Interval(pd.Timestamp("2020-01-01"), pd.Timestamp("2020-02-01"))
delta + interval
```

```python
UFuncTypeError                            Traceback (most recent call last)
<ipython-input-1-2c3b3a0b4fb8> in <module>
      4 delta = np.timedelta64(0)
      5 interval = pd.Interval(pd.Timestamp("2020-01-01"), pd.Timestamp("2020-02-01"))
----> 6 delta + interval

UFuncTypeError: ufunc 'add' cannot use operands with types dtype('<m8') and dtype('O')
```

Flipping the operands however works

```python
interval + delta
```

```python
Interval('2020-01-01', '2020-02-01', closed='right')
```