fix(ngAria): do not set aria attributes on input[type="hidden"]

This fixes a error found by @edclements  using the Google Accessibility Developer Tools audit.
Input fields of type hidden shouldn't have aria attributes.
https://www.w3.org/TR/html-aria/#allowed-aria-roles-states-and-properties-1

Closes #15113 
Closes #16367

BREAKING CHANGE:

ngAria no longer sets aria-* attributes on input[type="hidden"] with ngModel.
This can affect apps that test for the presence of aria attributes on hidden inputs.
To migrate, remove these assertions.
In actual apps, this should not have a user-facing effect, as the previous behavior 
was incorrect, and the new behavior is correct for accessibility.