Replacing Rails Asset Pipeline with Webpacker

I'll admit that I'm still relatively new to Rails Webpacker, but on a new project I've decided to completely replace the Sprockets asset pipeline and instead handle all my assets through Webpacker. As a fellow convention over configuration fan I've tried my best to interpret what the convention for structuring a Webpacker app is - I think it's still early days and even the Rails team haven't worked it out yet. I suspect it's something the community will nut out over time. Nonetheless, here is how I've replaced the asset pipeline in my app.