UPGRADE FROM 5.x to 6.0
=======================
FrameworkBundle
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* Removed `MicroKernelTrait::configureRoutes()`.
* Made `MicroKernelTrait::configureRouting()` abstract.
HttpFoundation
--------------
* Removed `Response::create()`, `JsonResponse::create()`,
`RedirectResponse::create()`, and `StreamedResponse::create()` methods (use
`__construct()` instead)
Routing
-------
* Removed `RouteCollectionBuilder`.
