feat(explorer): add filesystem watchers (#1304)

* feat(explorer): add experimental watchers

This commit introduces watchers to update the tree.
This behavior is introduced behind an "filesystem_watchers" option
which should prevent instabilities.
It will become the default at some point.

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

lua/nvim-tree/actions/copy-paste.lua

@@ -165,7 +165,9 @@ local function do_paste(node, action_type, action_fn)
   end
 
   clipboard[action_type] = {}
-  return require("nvim-tree.actions.reloaders").reload_explorer()
+  if not M.enable_reload then
+    return require("nvim-tree.actions.reloaders").reload_explorer()
+  end
 end
 
 local function do_cut(source, destination)
@@ -242,6 +244,7 @@ end
 
 function M.setup(opts)
   M.use_system_clipboard = opts.actions.use_system_clipboard
+  M.enable_reload = not opts.filesystem_watchers.enable
 end
 
 return M