Sets or gets a text input's value.
To reset the text box, restoring any placeholder text, set the value
property to null or undefined.
Notes:
Changing a text box's value in code does not trigger an onChange event.
If an element is connected to a dataset, setting the element's value
in code does not set the value of the connected field in the dataset.
That means if you use the dataset to perform a submit, the value changed
in code is not reflected in the submitted item.
To submit the new value using a dataset, set the field's value using the
setFieldValue() function before
performing the submit.