Fix: Change naming for the .add(text) methods for UIElement

[calebkleveter]

The UIElement has a couple of methods that set the text for the element. The problem is that they are called add. It should be set.

• [ ] Change the UIElement.add{Raw}(text) methods to UIElement.set{Raw}(text).
• [ ] Add UIElement.add{Raw}(text) methods.