Provide a checkbox value input

Problem/Motivation

There is a really common UI pattern where a user is asked to check a box before entering a value. This creates two values that need to handled/parsed when generally you only need to store the entered value.

For example, if a user wants to enable pattern validation they should check the 'Pattern' checkbox and then enter the Pattern's Regular Expression. Technically, on the entered pattern needs to be saved for an element. The checkbox can be checked when a pattern is defined.

Proposed resolution

Provide a checkbox value input.