LogicEditor | Refactor LoadScene node to present viable Scenes via Dropdown

Summary

The current implementation of the LoadScene node prompts users to enter the name of the scene that should be loaded.

Problem or need

User could enter wrong scene names or the names of scenes not valid for use (e.g. server start scenes included in the build).

Proposed solution

Use Figments.Utilities.SceneUtilities.GetValidScenes() to get the valid scenes and generate a dropdown from these.

Alternatives considered

N/A

Additional context