Consider splitting Text property of ToggleButton by state

[bruno-f-cruz]

I would argue that the default use of ToggleButton is likely to have a UI element that transitions between two states (On and Off). Currently, these two states are represented by the aspect change of the button, but not reflected via the Text property.

I would suggest to split the Text property in two distinct properties CheckedText and UncheckedText to allow easily assigning different text states to the button.

It should be noted that this behavior can be mimicked using already available logic by externalizing the property Text from the UI element. However, given the general use of the UI element, I believe this should be supported somewhat natively by the operator.