Ability to delete scratches

[ethteck]

Closes #308

If you wanna do the front-end work here as well, alex, happy to have it all in this PR. Otherwise, I will move this out of draft state and we can do that later. lmk

I'd imagine we want front-end delete buttons in a few different places:

• Scratch page
  • Frog-burger menu
  • Potentially elsewhere on the page as well?
• Scratch lists
  • User page
  • Family view
  • Project function attempts view

[ethteck]

https://discord.com/channels/897066363951128586/897075447534354462/1006946725061214372