Yes, it's a parameter to launch finsql.exe, the old C/SIDE development environment.
You can also enable a similar feature in the service tier settings.
I have tried these settings, some time ago, and they don't really work well. Hybrid development is better to be avoided, imho.
Anyway, after you apply the settings then someone downloading symbols in VSCode should be able to see what other have added/modified in C/SIDE. But be aware, C/SIDE will NOT be aware of any extensions you publish or objects you create/extend in VScode.
