There is no announcement for screenreaders that Save / Update Page action was successful

[bacitracin]

Issue Description

This issue was identified in the accessibility audit of the review & confirmation pages of the 526 form.

Expected severity: a11y-defect-1
Page: review-and-submit
Environment: any screenreader/browser combo
Estimated Level of Effort to fix: Medium
Design system component involved: Yes
Relevant WCAG success criteria: 4.1.3 Status Messages Level AA

To Reproduce:

• Use a screenreader and edit an item under one of the review accordions.
• Click Save or Update Page.

Expected Behavior

• There should be an announcement for the screenreader user that item has been updated/saved.

Actual Behavior

• There is no announcement that the change was successful.

Tasks

• Add/reuse an aria-live polite area to announce this change. It should not steal focus.
• Please update the "Fix Status" column in the 526 Accessibility Audit issues tracking doc when ticket is started and completed.

Acceptance Criteria

• Screenreader users hear that their change was successful.
• Accessibility Audit issue tracking doc is updated with ticket status