refactor(renderer): extract build line function

lua/nvim-tree/renderer/builder.lua

@@ -182,8 +182,7 @@ function Builder:_build_file(node, padding, git_highlight)
   end
 end
 
-function Builder:build(tree)
-  for idx, node in ipairs(tree.nodes) do
+function Builder:_build_line(tree, node, idx)
   local padding = pad.get_padding(self.depth, idx, tree, node, self.markers)
 
   if self.depth > 0 then
@@ -209,6 +208,11 @@ function Builder:build(tree)
     self:build(node)
     self.depth = self.depth - 2
   end
+end
+
+function Builder:build(tree)
+  for idx, node in ipairs(tree.nodes) do
+    self:_build_line(tree, node, idx)
   end
 
   return self