Consider adding an `aria-modified` prop so we can mark a field both `aria-required` &/or `aria-modified`

[fbarroso24]

Description of bug or feature request

The lists of aria props includes an aria-required prop to indicate that user input is required on the element before a form may be submitted. However, I was surprised to find that an aria-modified prop did not exist to denote an input field has been modified.

The only thing I could find regarding modification are props to support live regions to announce changed/inserted content within that region. However, this doesn't provide the granularity required in order to know which inputs have been modified like it does with the aria-required prop.

Use Case We have fields in a form and often times it is useful to inform the users which fields have been modified. This is useful so that they know which fields will be updated if they decide to Save.

Workaround Currently we use a black * positioned before a field label and a red * positioned after a field label to convey a modified &/or required field respectively. This relies on color & location of the * to convey whether a field is required, modified or both.

However, it'd be great if we could use aria-required & this new aria-modified prop as a 3rd way to convey the modified status for a field given that some screen readers will read the * as either star or asterisk instead of required (e.g. star Name star)

Will this require a change to CORE-AAM?

I'm not sure

Will this require a change to the ARIA authoring guide?

If we add an aria-modified prop then we'd likely need to document it in the list of aria props likely via an anchor like https://www.w3.org/TR/wai-aria-1.2/#aria-modified