More school features

It would be cool if we could try appealing more to schools and teachers. Some ideas would be a way to work with extension policies, a system for teachers to create classes and assignments, and students to be able to attach projects to them. Additionally, ScratchTools community-based features don't really appeal quite as much to teachers and those kinds of uses, so a focus on editor features for a bit could be ideal if this is the direction we choose to go for a bit.