Ship with an empty public folder, rather than intermixing build and git-tracked assets

[pwolanin]

Since we moved to a github pages deploy, it would make things easier to understand if the target "public" folder had no assets tracked in git (i.e. was git ignored) and all the assets under git control were in more clearly documented locations.

To make this work, we basically need to add to webpack a step to copy those assets to the public folder using something like the copy-webpack-plugin. Looks like we'd have to use something like v 4.6.0 with the current outdated node version used to build

https://v4.webpack.js.org/plugins/copy-webpack-plugin/
https://github.com/webpack-contrib/copy-webpack-plugin/tree/v4.6.0