implement antd ConfigProvider

NBSV is one of the Simularium front-ends using antd 5, which uses a `ConfigProvider` and a CSS-in-JS approach where antd4 used LESS variables and more emphasis on accessing class names in stylesheets. 

Implementing a `ConfigProvider` and, possibly other CSS-in-JS tools, will bring our front-end styling more in line with the ant version we are using.