rewrite visual forms using react instead of jQuery

[shapiromatron]

This PR should be reviewed after #1114

There were a few legacy jQuery applications for building custom visuals in HAWC. These user-interfaces did not perform well and had some bugs, but because they were so complicated, we never were able to fix them and they remained in this painful state. Because of the inability to change the applications, we had a really complicated django view and form layout too, since we had multiple different approaches depending on the frontend technology being used. This PR removes the jQuery applications and fully switch to a react frontend. This should dramatically improve stability of the application.

This rewrites the form frontend for Crossview, RobHeatmap, and RobBarchart.

In addition:

• Refactor and standardize visual form startup javascript
• Rewrite how the django-form panel is being used in React. Instead of recreating the django form with React, we have move the form in the react tab, and then out of the react tab, so that we're not duplicating state.
• Rewrite the dose units selector widget to use React instead of the jQuery custom solution. See PreferredWidget.
• Added tests to improve test coverage for the diversity of visual types and evidence types
• Remove VisualizationCreateTester
• Refactor how data for preview of visualizations is generated and passed to the application.