Use `any` and `all` to make collection non-optional

I have seen patterns like this several times:
```python
def func() -> Optional[int]:
    pass

def test() -> List[int]:
    vals: Iterable[Optional[int]] = [func() for _ in some_list]
    if all(vals):
        return list(vals)  # None can't be in 'vals' here.
    return []
```
It would be convenient if binder could understand this for covariant collections.