UHF-7853: Notification components accessibility

[jeremysteerio]

UHF-7853

Some accessibiity work for announcement and status message components

What was done

• Add preprocess hook too expose accessibility-related variables to announcements template
• Implement accessibiity fixes to announcement and status message templates

How to install

• Boot up an instance of your choice
• Get this branch. composer require drupal/hdbt:dev-UHF-7853-notification-components-accessibility

How to test

• Create 3 instances of announcements (/node/add/announcement) and select a different type for each of them. Make sure that all have "Show on all pages" option checked.
• After you save the last of them, Drupal should redirect you to the announcement's node page. On this page you should see:
  • All the announcements you created
  • Drupal's status message informing you that that you have just published an announcement

Check for these things:

In the Drupal's status message:

• Root container should no longer have role=contentinfo or aria-labelledby attributes

In the announcement component:

• Root container should now be a section element with an aria-label informing the use of the announcement's type
• Close button aria label should now read Close [announcement type] instead of being a static Close announcement

Designers review

• This PR does not need designers review
• This PR has been visually reviewed by a designer (Name of the designer)