fix(Pagination): Add announcement when selected page updates.

[olehnoskov-cengage]

Closes: #2025

What I did

• Added announcement for Pagination when the selected page changes.

Screenshots

Checklist

• [x] changeset has been added
• [x] Pull request is assigned, labels have been added and ticket is linked
• [x] Pull request description is descriptive and testing steps are listed
• [ ] Corresponding changes to the documentation have been made
• [ ] New and existing unit tests pass locally with the proposed changes
• [ ] Tests that prove the fix is effective or that the feature works have been added

How to test

Go to Storybook -> Pagination -> Default -> Turn on VO/NVDA -> when the selected page changes -> screen reader announces the selected page number.

Go to Storybook -> Pagination -> Simple Pagination -> behaviour should work as before.