Gives you the DOM element id that will be used by a TextInput.view with the given label.
This is for use when you need the DOM element id for use in javascript (such as trigger an event to focus a particular text input)
NOTE: this uses inputmode="email" so that mobile devices will use the email keyboard,
but not type="email" because that would enable browser-provided validation which is inconsistent and at odds
with our validation UI.