fix: expand and collapse whole folder groups (#2380)

* fix: expand and collapse whole folder groups

* refactor: rename some usages of `next`

---------

Co-authored-by: Alexander Courtis <alex@courtis.org>

lua/nvim-tree/lib.lua

@@ -74,11 +74,21 @@ end
 
 -- If node is grouped, return the last node in the group. Otherwise, return the given node.
 function M.get_last_group_node(node)
-  local next = node
-  while next.group_next do
-    next = next.group_next
+  local next_node = node
+  while next_node.group_next do
+    next_node = next_node.group_next
   end
-  return next
+  return next_node
+end
+
+function M.get_all_nodes_in_group(node)
+  local next_node = utils.get_parent_of_group(node)
+  local nodes = {}
+  while next_node do
+    table.insert(nodes, next_node)
+    next_node = next_node.group_next
+  end
+  return nodes
 end
 
 function M.expand_or_collapse(node)
@@ -90,8 +100,10 @@ function M.expand_or_collapse(node)
     core.get_explorer():expand(node)
   end
 
-  node = M.get_last_group_node(node)
-  node.open = not node.open
+  local open = not M.get_last_group_node(node).open
+  for _, n in ipairs(M.get_all_nodes_in_group(node)) do
+    n.open = open
+  end
 
   renderer.draw()
 end