refactor(#2886): multi instance: node group functions refactoring (#2959)

* move last_group_node to DirectoryNode

* move add BaseNode:as and more doc

* revert parameter name changes

* revert parameter name changes

* add Class

* move group methods into DN

* tidy group methods

* tidy group methods

* tidy group methods

* tidy group methods

* parent is DirectoryNode

* tidy expand all

* BaseNode -> Node

* move watcher to DirectoryNode

* last_group_node is DirectoryNode only

* simplify create-file

* simplify parent

* simplify collapse-all

* simplify live-filter

* style

lua/nvim-tree/api.lua

@@ -10,6 +10,7 @@ local keymap = require("nvim-tree.keymap")
 local notify = require("nvim-tree.notify")
 
 local DirectoryNode = require("nvim-tree.node.directory")
+local RootNode = require("nvim-tree.node.root")
 
 local Api = {
   tree = {},
@@ -137,9 +138,9 @@ Api.tree.change_root = wrap(function(...)
 end)
 
 Api.tree.change_root_to_node = wrap_node(function(node)
-  if node.name == ".." then
+  if node.name == ".." or node:is(RootNode) then
     actions.root.change_dir.fn("..")
-  elseif node.nodes ~= nil then
+  elseif node:is(DirectoryNode) then
     actions.root.change_dir.fn(node:last_group_node().absolute_path)
   end
 end)
@@ -210,13 +211,13 @@ local function edit(mode, node)
 end
 
 ---@param mode string
----@return fun(node: table)
+---@return fun(node: Node)
 local function open_or_expand_or_dir_up(mode, toggle_group)
+  ---@param node Node
   return function(node)
     if node.name == ".." then
       actions.root.change_dir.fn("..")
     elseif node:is(DirectoryNode) then
-      ---@cast node DirectoryNode
       node:expand_or_collapse(toggle_group)
     elseif not toggle_group then
       edit(mode, node)