Building on the previous commit to invoke not invoke `npm install` this takes
the commit a step further (to hopefully fix some races) to use Webpack's native
bundled wasm support.
It turns out the circular dependencies between the wasm module and the module
using it wasn't quite working out so a number of imports had to be tweaked, but
otherwise it's a nice transition where we don't have to base64 encode anything
in tests any more!
