Editor experience

You should be able to add one and only one Cart or Checkout block to a page.
The preview in the inserter should show a skeleton of how the block structure should look like.
When inserting any of the blocks, it should have some data already in it.
You should not be able to interact directly with the block (except for some sections).
You should be able to see block settings on the sidebar when it is focused.
Proceed to Checkout and Back to cart block settings should present you with a list of your website pages.