change to root logger affects other projects

**Describe the bug**
Open3D append to the Python root logger which in return yields doubled log messages when setting a logging handler in another project.

**To Reproduce**
Steps to reproduce the behavior:

```py
import logging
print(logging.getLogger().handlers) # > []
import opend3d
print(logging.getLogger().handlers) # > []
```

**Expected behavior**
Open3D should use `logging.getLogger(__name__)` and only change the open3D logger and not others.
This should give
```py
print(logging.getLogger(__name__).handlers) # > []
```
where `__name__ == "open3d"`