Option for $ignoreUnknownDescendants

[TetyLike3]

I ran into an issue where child folders don't ignore unknown instances even if their parent does. I'd prefer to have a mock of the folder structure on my local repository so that I'm absolutely sure I'm looking at the right directories for certain things.
I was looking at #182 and saw that it was both dead and someone recommended to make a new issue, but I had a quick look and saw that there weren't any other relevant issues. There also doesn't seem to be any alternatives mentioned other than explicitly telling Rojo that those child folders should also ignore unknown instances, which isn't convenient as I'd have to go back to edit the project.json every time I add a new folder.