Add tests for get_node autocompletion

[HolonProduction]

Requires #86961

[Mickeon]

A whooping 100 files added. Are they all truly necessary for the tests?

[HolonProduction]

A whooping 100 files added. Are they all truly necessary for the tests?

Yeah the file count kinda exploded 😅. But every idea I have to reduce it seems worse.

• Each test needs at least 2 Files. That makes 50 test, but some of them are duplicated in different call situations (yes this is needed, see for example #72328 and there also was another one that i cant find rn 😞). So we are at ~30 test, and I plan to do more, not reduce them. For something as complex as this, reducing tests doesn't seem like a good idea.
• I often have test which require the same output for multiple files. But specifying script paths inside of the cfg files, would make it harder to find the right cfg. And I don't wan't to have multiple scripts inside of the same file, since it would introduce yet another "magic" character to separate them.
• We could reduce each test into one file, but this would either require a sort of preface for the GDScript and parsing that would be annoying. Or we could embed the GDScript inside the cfg, but that would make it impossible to test something manually by opening the script in the editor.

If you have any other ideas to reduce it, I'm all in for it, that being said many test files aren't that big of a problem to justify any of the tradeoffs that I listed IMO.

[HolonProduction]

Waiting for #87759 in order to fix the CI.

[HolonProduction]

Ready for review

[vnen]

On a cursory look it is good to me. Thanks for working on this!

[akien-mga]

Thanks!

[HolonProduction]

Oh shit, I just noticed I forgot to squash the commits and now you merged it 😅. I guess it can't be changed now?

[akien-mga]

Yeah I missed that. It can't be changed once merged.