refacto: move some code into actions

(non breaking, old assignments link to new assignments)
- move lib.collapse-all into actions/collapse-all
- move lib.dir-up into actions/dir-up
- move lib.change-dir into actions/change-dir
- use setup option for change-dir global (and use the old option for
  setup)

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

@@ -0,0 +1,19 @@
+local M = {}
+
+function M.fn()
+  local function iter(nodes)
+    for _, node in pairs(nodes) do
+      if node.open then
+        node.open = false
+      end
+      if node.entries then
+        iter(node.entries)
+      end
+    end
+  end
+
+  iter(require'nvim-tree.lib'.Tree.entries)
+  require'nvim-tree.lib'.redraw()
+end
+
+return M