Point set tools are not displayed

## Overview

When trying to view a point set in a scene by itself the individual points are very small. From conversation with @PaulHax it sounds like there are existing tools for adjusting point size that are intended to be displayed, but are not.

## Expected behavior

Tools are available to adjust point set size and possibly other details such as point color.

## Observed behavior

3D points are displayed, but no tool is given for adjusting point size. Default size is small, white points that are hard to see against light gray background.


## Versions

itkwidgets==1.0a22
itk==5.3.0
notebook==6.1.6

## Platforms

Windows 10
Google Chrome browser

## Other notes

- In the screenshot above, `type(input_points)` is `itk.itkPointSetPython.itkPointSetF3`
- Screenshots of landmark points in the [`ThinPlateSpline.ipynb` example notebook](https://github.com/bnmajor/itkwidgets/blob/c9ff7ed9fb073ca060bde2a15deba4367e029697/examples/integrations/itk/ThinPlateSpline.ipynb) on GitHub seem to show similar behavior.