support nested method calls like `each('order.line_items', A, B, C)`

This is a common enough use case and the alternative is a little ugly:

```ruby
organize \
  -> { _1.line_items = _1.order.line_items },
  each(:line_items, A, B, C)
  ```
  
  VS
  
  
```ruby
organize each('order.line_items', A, B, C)
```

Gut feeling suggests we can allow arbitrary length method chaining, but we should raise when the returned value is not Enumerable