deleted folder still lives in project view

[eleanorjboyd]

1. create a package project with a new env created
2. confirm it updates the settings with the new project
3. delete the package folder
4. 🐛 check the settings, it still exists there
5. 🐛 check the UI for the workspace projects, the deleted folder still exists there

[eleanorjboyd]

@karthiknadig my plan for implementation is to add a listener to see if a proejct file/folder is deleted. Lmk if this is the right approach to use a listener in this way. Also I guess it would be best if on ext restart it confirms all folders / files still exist before adding to the project view in case something occurred while the ext was closed.