Use editor GDExtension support when it lands in Godot for demo project

[limbonaut]

Use editor support for C++ extensions in the jump demo project when such support lands in Godot.

Godot PR:

• Allow creating GDExtension plugins from inside the Godot editor godotengine/godot#90979

"Jump" demo project:

• https://github.com/sentry-demos/godot