refs #4172
* 🎨 Use bodyParser only where it is needed
This is a pretty extreme optimisation, however in the interests of killing middleware/index.js it
seemed prudent to move towards not having in there that wasn't strictly necessary 😁
We should reassess how apps do this sort of thing, but it seems pretty sane to declare bodyParsing
if and only if it is necessary.
* 🎨 Move all API code to API router
* 🎨 Refactor API into an App, not just a router
- Apps have their own rendering engines, only the frontend & the admin panel need views
- The API should be JSON only, with minimal middleware
- Individual sections within the API could/should be treated as Routers
* 🎨 Flatten API middleware inclusion
- get rid of the weird middleware object
- move the api-only middleware into the middleware/api folder
