feat(event): add WillRenameNode (#1821)

lua/nvim-tree/events.lua

@@ -6,6 +6,7 @@ local global_handlers = {}
 
 M.Event = {
   Ready = "Ready",
+  WillRenameNode = "WillRenameNode",
   NodeRenamed = "NodeRenamed",
   TreeOpen = "TreeOpen",
   TreeClose = "TreeClose",
@@ -40,6 +41,11 @@ function M._dispatch_ready()
   dispatch(M.Event.Ready)
 end
 
+--@private
+function M._dispatch_will_rename_node(old_name, new_name)
+  dispatch(M.Event.WillRenameNode, { old_name = old_name, new_name = new_name })
+end
+
 --@private
 function M._dispatch_node_renamed(old_name, new_name)
   dispatch(M.Event.NodeRenamed, { old_name = old_name, new_name = new_name })