[Work Item] Handle Category hierarchy properly

[Jake-Pullen]

Goal

Currently when adding Categories, we can add a parent just fine, however we can add an unlimited amount of parent / child relationships meaning an overly flexible hierarchy.
We need to not allow more than 3 tier hierarchy
We also need to display that hierarchy structure on the front end and not just a list of all categories
Im thinking something simple for now like:

• Parent Category
  • child 1
    • grandchild 1
  • child 2
• Parent Category 2
• Parent Category 3
  • child 1
  • child 2