Bulk actions (cut, copy, delete)

[taramk]

I can sometimes highlight multiple nodes to select them (to bulk delete) if I drag from the top rather than the bottom, but hitting delete on the keyboard does not delete them.

• make click and drag to highlight multiple nodes work consistently
• allow selecting multiple nodes and deleting them using the delete keyboard key

[progrium]

This is two things: multi selection and multi operation. I don't exactly know how to do click+drag multi selection yet. Text showing as selected is totally separate. I do know how to let you do something like shift click for selecting multiple nodes. But also might want to consider how multi selection would work on mobile. Luckily delete is a simple multi operation, so it's a good first case.

[taramk]

For highlight color, I suggest our teal (0193B3) at 30% opacity. It's the most visible without being too obtrusive on light/medium/dark backgrounds. For now it should just be a static value, maybe later it can be a theme variable.

https://www.figma.com/file/bGzEZo0NYHhWGJO95kwF3p/Treehouse-App?type=design&node-id=426%3A5624&mode=design&t=Yo9VmF4v4sMvd8dh-1