[Bug][a11y]: A screen reader should announce a Toast message when it is added to the DOM

### Code of conduct

- [X] I agree to follow this project's code of conduct.

### Impacted component(s)

Toast

### Expected behavior

A screen reader should announce a Toast message when it is added to the DOM. A develop should not need to remember to add `role="status"` or `role="alert"` so that assistive technology will announce the message.

### Actual behavior

A screen reader will not announce a Toast message when it is added to the DOM, without additional developer awareness to add role="status" or role="alert."

### Screenshots

_No response_

### What browsers are you seeing the problem in?

_No response_

### How can we reproduce this issue?

1. Go to '...'
2. Click on '....'
3. Scroll to '....'
4. Check console
5. See error

### Sample code that illustrates the problem

_No response_

### Logs taken while reproducing problem

_No response_

Start by locating the Toast component and reviewing how its DOM updates are exposed to assistive technology. Reproduce the issue with a screen reader, then verify that a Toast added to the DOM is announced without requiring consumers to add an accessibility role.

Written by the indexing model from the issue text.