Create custom UI?

[simonihmig]

Goals:

• have a nicer Look & Feel, ideally Ember-ish. sourcemap-explorer (Refactor to use source-map-explorer, enabling usage with Ember CLI, ember-auto-import and Embroider #26) has an ugly UI
• allow customization of output (e.g. sourcemap-explorer's gzip sizes are weird)
• eventually allow for filtering (e.g. initial load vs. lazy loading vs. tests)

webpack-bundle-analyzer uses https://carrotsearch.com/foamtree/, but we could also create our own UI using d3 (https://observablehq.com/@d3/treemap).