Adding webpack-build-analyzer to react-digraph

[rileyhilliard]

☝️ example output of `yarn analyze-bundle`

Adding webpack-build-analyzer to react-digraph, and wiring up the necessary tooling
How to use this:

1. install via yarn or npm install
2. run yarn analyze-bundle or npm run analyze-bundle
3. once the analyzer is finished, it will open a new browser tab with the results

Resolved #106

[CLAassistant]

All committers have signed the CLA.

[rileyhilliard]

@ajbogh / @chiwoojo once this is in I can help trim about 2/3's of the build output from the production build

[ajbogh]

I've checked this out and found that it works. Thanks!