fix(#2945): stack overflow on api.git.reload or fugitive event with watchers disabled (#2949)

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

This reverts commit 50e919426a.

* fix(#2945): stack overflow on api.git.reload or fugitive event

lua/nvim-tree/node/root.lua

@@ -0,0 +1,20 @@
+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