Add support for binary stars in space

[jorisvddonk]

Binary stars in Noctis IV can be pretty exciting. It'd be nice if they're properly supported, i.e. if the "planet class" 11 ("Companion star - not a planet.") shows as a proper star in space as well.

This very likely only requires changes in the Godot project - and not changes in feltyrion-godot -, hence why it's marked as a "good first issue". That said, it may be a good idea to do some larger refactoring to ensure that stars and companion stars both use some new internal scene dedicated to displaying in-system stars. Whomever picks this issue up may want to spend some time understanding the current scene layout and project structure.

[jorisvddonk]

An initial version doesn't have to be perfect; as long as it shows a star that visually looks like any other star, I'll accept a PR! We can make stars look more accurate or exciting later.