refactor: improve API readability and tidy actions submodules (#2593)

* refactor: improve API readability, tidy actions modules

* Apply requested changes

* `actions/reloaders/reloaders.lua` -> `actions/reloaders.lua`

---------

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

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

@@ -0,0 +1,53 @@
+local renderer = require "nvim-tree.renderer"
+local utils = require "nvim-tree.utils"
+local core = require "nvim-tree.core"
+local lib = require "nvim-tree.lib"
+local Iterator = require "nvim-tree.iterators.node-iterator"
+
+local M = {}
+
+---@return fun(path: string): boolean
+local function buf_match()
+  local buffer_paths = vim.tbl_map(function(buffer)
+    return vim.api.nvim_buf_get_name(buffer)
+  end, vim.api.nvim_list_bufs())
+
+  return function(path)
+    for _, buffer_path in ipairs(buffer_paths) do
+      local matches = utils.str_find(buffer_path, path)
+      if matches then
+        return true
+      end
+    end
+    return false
+  end
+end
+
+---@param keep_buffers boolean
+function M.fn(keep_buffers)
+  local node = lib.get_node_at_cursor()
+  local explorer = core.get_explorer()
+
+  if explorer == nil then
+    return
+  end
+
+  local matches = buf_match()
+
+  Iterator.builder(explorer.nodes)
+    :hidden()
+    :applier(function(n)
+      if n.nodes ~= nil then
+        n.open = keep_buffers == true and matches(n.absolute_path)
+      end
+    end)
+    :recursor(function(n)
+      return n.group_next and { n.group_next } or n.nodes
+    end)
+    :iterate()
+
+  renderer.draw()
+  utils.focus_node_or_parent(node)
+end
+
+return M