* basic e2e tests for cart block:
- can add block, confirm editor markup matches snapshot
- can only insert one cart block
* add basic tests for checkout block:
- can add & matches snapshot
- can only add one block
* confirm single-cart test works, by allowing multiple cart blocks :)
* Revert "confirm single-cart test works, by allowing multiple cart blocks :)"
This reverts commit aae10046f37bc53bf11d8d2e1deb626d53654f71.