feat(web-preview): add ESC key support and dynamic titles for segments and prompts

[thomasguillot]

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 enhances the web preview component with keyboard support and contextual titles.

Changes:

• Adds ESC key support to close the web preview modal (improved accessibility)
• Displays segment name in preview modal title when previewing segments (better UX with contextual information)
• Displays prompt name in preview modal title when previewing prompts

How to test the changes in this Pull Request:

Test ESC Key Functionality

1. Navigate to Audience Management > Campaigns
2. Click the "Preview Segment" button on any segment group
3. Verify the preview modal opens
4. Press the ESC key
5. Verify the modal closes
6. Repeat steps 2-5 for a prompt preview (click preview on any prompt card)

Test Segment Title in Preview

1. Navigate to Audience Management > Campaigns
2. Click the "Preview Segment" button on any segment group
3. Verify the modal toolbar displays "Segment: {segment name}" (e.g., "Segment: Subscribers")
4. Close the modal

Test Prompt Title in Preview

1. Navigate to Audience Management > Campaigns
2. Find any prompt card in a segment group
3. Click the preview button/icon on the prompt card
4. Verify the modal toolbar displays "Prompt: {prompt title}" (e.g., "Prompt: Newsletter Signup")
5. Close the modal

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?