Create a target label to show limits

[serralvo]

The idea is provide a way to show the information about limits in an external label, by default, we keep using internal label (as right view).

[rogerluan]

Low priority imo. Do it if/when you need it, or if/when many people request it. :) Pros: you make the rightView available to be used for other purposes! Cons: low usage/adoption rate imo. In other words, not so many users of this text field actually need to use the rightView for other purposes.