feat(notify): add notify.threshold (#1693)

* feat: configurable notification level

add `notify.threshold` to setup opts

* feat: configurable notification level: add threshold example doc

* feat: configurable notification level: log always comes last

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

lua/nvim-tree/actions/tree-modifiers/expand-all.lua

@@ -1,7 +1,7 @@
 local core = require "nvim-tree.core"
 local renderer = require "nvim-tree.renderer"
-local utils = require "nvim-tree.utils"
 local Iterator = require "nvim-tree.iterators.node-iterator"
+local notify = require "nvim-tree.notify"
 
 local M = {}
 
@@ -58,7 +58,7 @@ end
 function M.fn(base_node)
   local node = base_node.nodes and base_node or core.get_explorer()
   if gen_iterator()(node) then
-    utils.notify.warn("expansion iteration was halted after " .. M.MAX_FOLDER_DISCOVERY .. " discovered folders")
+    notify.warn("expansion iteration was halted after " .. M.MAX_FOLDER_DISCOVERY .. " discovered folders")
   end
   renderer.draw()
 end