Revert "yarn: update react-complex-tree to v2.0.0"

This reverts commit f0434b50ed.

This requires react >= v18

src/explorer/Explorer.tsx

@@ -370,7 +370,7 @@ const FileTree: React.VoidFunctionComponent = () => {
                     [rootItemIndex]: {
                         index: rootItemIndex,
                         data: { fileName: '/' },
-                        isFolder: true,
+                        hasChildren: true,
                         children: [...files].map((f) => f.uuid),
                     },
                 } as Record<TreeItemIndex, FileTreeItem>,

src/utils/tree-renderer.tsx

@@ -99,7 +99,7 @@ export const renderers: Omit<
                         )}
                         {...props.context.itemContainerWithoutChildrenProps}
                     >
-                        {props.item.isFolder ? (
+                        {props.item.hasChildren ? (
                             props.arrow
                         ) : (
                             <span className={Classes.TREE_NODE_CARET_NONE} />