joinListUp
If the text cursor is at the start of the first child of a list node, lift all content inside the list. If the text cursor is at the start of the last child of a list node, lift this child.
const joinListUp: Command;
If the text cursor is at the start of the first child of a list node, lift all content inside the list. If the text cursor is at the start of the last child of a list node, lift this child.