Submission Review Guidelines:

• I have followed the WooCommerce Contributing Guidelines and the WordPress Coding Standards.
• I have checked to ensure there aren't other open Pull Requests for the same update/change.
• I have reviewed my code for security best practices.
• Following the above guidelines will result in quick merges and clear and detailed feedback when appropriate.

Changes proposed in this Pull Request:

Add button on product description toolbar to toggle show/hide block inspector

Closes #39025 .

How to test the changes in this Pull Request:

Using the WooCommerce Testing Instructions Guide, include your detailed testing instructions:

1. Enable "Try the new product editor (Beta)" in WooCommerce > Advanced > Features.
2. Go to Product > Add New.
3. Click "Add Description".
4. Check the button on the top right of the modal.
5. Click it and check if it shows/hides the block inspector.

Changelog entry

• Automatically create a changelog entry from the details below.