open3d.io.read_point_cloud only loads 3 dimensions from pcd file, how do I load all dimensions?

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

When using the following example file
```
# .PCD v.7 - Point Cloud Data file format
VERSION .7
FIELDS x y z h s v
SIZE 4 4 4 4 4 4
TYPE F F F F F F
COUNT 1 1 1 1 1 1
WIDTH 3
HEIGHT 1
POINTS 3
DATA ascii
0.93773 0.33763 0 4.2108e+06 0 0
0.90805 0.35641 0 4.2108e+06 0 0
0.81915 0.32 0 4.2108e+06 0 0
```

Loading the file with open3d
```
>>> import numpy as np
>>> import open3d
>>> np.asarray(open3d.io.read_point_cloud("test_case.pcd", "pcd").points)
array([[0.93773, 0.33763, 0. ],
[0.90805, 0.35641, 0. ],
[0.81915, 0.32 , 0. ]])
```

Loading the file with pypcd
```
>>> from pypcd import pypcd
>>> pypcd.PointCloud.from_path("test_case.pcd").pc_data
array([(0.93773, 0.33763, 0., 4210800., 0., 0.),
(0.90805, 0.35641, 0., 4210800., 0., 0.),
(0.81915, 0.32 , 0., 4210800., 0., 0.)],
dtype=[('x', '