In IDEs, blocks are often associated with folding. For example in VS Code: Unfolded: <img width="506" alt="image" src="https://github.com/TypeCellOS/BlockNote/assets/98301/5b6ef11c-d913-40b6-b9ec-fd2f9a62e4d2"> Folded: <img width="327" alt="image" src="https://github.com/TypeCellOS/BlockNote/assets/98301/98cc5f58-c922-44f4-a98e-fdbd2f0d8a6a"> Is there support for folding in BlockNote? Has anyone built this feature on top of BlockNote? Would it be straightforward to add?