Update Notification component to have Button right-aligned by default with option for left-align

[cathystoli]

Background

During a discussion on Dialogs the SDS design team reached the decision that by default buttons should be right-aligned within Notifications and Dialogs with an included prop to optionally allow them to be left-aligned for those products (IDseq and Aspen) that have had left-aligned buttons from the beginning.

Acceptance Criteria:

• [x] Update Notification component to include a prop that allows for the button to be left-aligned or right-aligned; set it to right-aligned by default
• [ ] Update documentation in Zeroheight to reflect this new change
• [ ] Create eng implementation ticket to update current Notification component