feat(a11y): added ariaInvalid and ariaDescribedby props to SDP

[jrparish]

• ariaInvalid allows for more accessible form validation
• ariaDescribedby allows users to use custom elements for the field description instead of the built in screenReaderMessage behavior.

[ljharb]

Can you elaborate on "allows for more accessible form validation"?

[jrparish]

Can you elaborate on "allows for more accessible form validation"?

This attribute can be set to let a screen reader know a field is not valid.
For instance, a form may require a proper date. Say a user types in a partial date, which is invalid for the form, we would set aria-invalid to true to indicate to the user that the field is not correct.

[backwardok]

Changes look good to me from the a11y side!

I'll let someone who's more familiar with the codebase at large to give the approval.