[FEATURE] Migrate SceneTransitionManager to a project settings window

[japtar10101]

Is your feature request related to a problem? Please describe.

Scene Management.

Describe the solution you'd like

It seems Unity is opening up the API to add windows under Project Settings and Preferences. Since the scene management is shared across the entire project, it'd be better to move the feature to both a ScriptableObject and a Project Settings window. If possible, it should also monitor and automatically add new scenes (or list all the scenes) from the build settings.

Tasklist

• Look into whether Project Settings data can be accessed on runtime.
• If not, look into the effort of creating a ScriptableObject.
• Look into the effort necessary to check if new scenes are being added into the build settings, and actively updating the settings accordingly.

Describe alternatives you've considered

The current method, which everything is stored in a Singleton prefab. Not useful, as the information is likely not needed to be set on runtime.

Additional context

Part of an effort to decouple a lot of the Singleton scripts. See Issue #19 .