All Submissions:

• Have you followed the Newspack Contributing guideline?
• Does your code follow the WordPress' coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

This PR updates the dashboard and sidebar menu icons for Advertising and Newsletter Ads, making them more distinguishable while maintaining a cohesive look. This helps clarify why there are two Advertising cards, reducing potential confusion.

Before

After

How to test the changes in this Pull Request:

1. Switch to this branch
2. Check that the "Pullquote" icon has been replaced by the "Ad" icon and the "Envelope + Ad" icon

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?