Revert "refactor(#2871, #2886): multi instance: node classes created (#2916)"

This reverts commit 38aac09151.

lua/nvim-tree/node/root.lua

@@ -1,20 +0,0 @@
-local DirectoryNode = require("nvim-tree.node.directory")
-
----@class (exact) RootNode: DirectoryNode
-local RootNode = DirectoryNode:new()
-
----Static factory method
----@param explorer Explorer
----@param absolute_path string
----@param name string
----@param fs_stat uv.fs_stat.result|nil
----@return RootNode
-function RootNode:create(explorer, absolute_path, name, fs_stat)
-  local o = DirectoryNode:create(explorer, nil, absolute_path, name, fs_stat)
-
-  o = self:new(o) --[[@as RootNode]]
-
-  return o
-end
-
-return RootNode