Allow multiple Mailchimp forms on a single page.

[iamdharmesh]

Description of the Change

As mentioned in #172, we now support separate lists for each block, multiple forms on a single page should be allowed. This PR make changes to allow multiple forms on a single page.

Closes #172

How to test the Change

1. Create a page.
2. Add a Form block, then add another Form block and save the page.
3. Visit the page on the front end and ensure both forms are functional without any issues.
4. Switch to a block theme if you're not already using one.
5. Open the Site Editor and add a Subscribe Form in the footer.
6. Create a new page, add a form to the page, and save it.
7. Visit the page and confirm that both the footer form and the page form are working correctly.

Changelog Entry

Changed - Allowed multiple Mailchimp forms on a single page.
Changed - Updated form ID and form field IDs. (If you're using ID selectors for custom styling, please update the selectors accordingly.)

Credits

Props @iamdharmesh

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[qasumitbagthariya]

QA Update ✅

---

I have verified this PR in the enhancement/172 branch, which has been fixed and is functioning as intended.

I tested the following on this branch:

• Verified that multiple forms, two on a page and one in the footer, function correctly on the front end after creation and theme switch.

Screen.Recording.2025-07-23.at.2.34.50.AM.mov

Screen.Recording.2025-07-22.at.7.59.12.PM.mov

Testing Environment

• WordPress: 6.8.2
• Theme: Storefront 4.6.1
• Theme: Twenty Twenty-Four 1.3
• PHP: 8.0.30
• Web Server: Nginx 1.20.2
• Browser: Chrome
• OS: macOS 15.2
• Branch: enhancement/172

cc @vikrampm1