Make it easier to handle extended transition configuration

## Is your feature request related to a problem? Please describe.
The `SceneTransitionConfiguration` can be extended to add game-specific transition-time configurations.
The amount of code needed to extend the class is relatively large.

* The extended class itself
* A static method that downcasts the original class into the extended class
* Builder methods
* Extension function for the original class that calls the static upcasting method
(which allows the user to integrate the upcast into builder method chaining.)

## Describe the solution you'd like
Not yet discussed; I want to add something that can reduce the amount of code on the user side.

## Describe alternatives you've considered
N/A

## Additional context
N/A