Feature request: emptyDir() - exclude files/folders from being deleted#1015

Hello, I have a use case where I want to empty a folder, but keep some of the files/folders in that folder if they exist. If you're curious about my use case - I have a function that initializes a new node project in a specified directory and then runs `npm install`. If that directory already has a node_modules folder, I would like to keep the folder so that the node modules wouldn't need to be unnecessarily re-installed when running `npm install` Thanks! *P.S* I can make a PR for this too, but I would first like to know if this is something that the owners of the package would approve of.