Editor sidebar: bulk duplicate and delete, visibility indicator

[peterqliu]

This might be my own specific wishlist for editor sidebar UI, but it would greatly streamline working across multiple vals in a project:

• highlight vals to duplicate or delete them at once (analogous to the current move behavior)
• some indicator of whether val is private/unlisted/public (it's easy to forget to open up a val dependency when sharing a big project with many vals, so scanning that en masse is helpful)

[peterqliu]

also, duplicating a folder of vals (ostensibly adding a suffix to all val names)