Update d3

[Freddyerf]

Summary

Updated D3.js version to v7. Modified files to adhere to new conventions

• Instead of a blanket import d3, use specific imports
• Event parameters changed - event is passed in and used instead of d3.event

[andymeneely]

This is looking good! All the changes make sense to me. Gonna try it out locally to see how it works.

[andymeneely]

@JoshuaHAvi I added you as a reviewer as an FYI that we're doing this update - you'll likely need to update your code too. Hit approve to acknowledge