Voting feature

When a product is "coming soon", a voting form is added under the label, allowing visitors to vote for the products they want the most.

The admins can then see in the dashboard which products are most wanted and prioritize the development of new products. A count of the votes is also available on each product page, right under the "Coming soon" checkbox.
Rather than using a constant to enable voting with a filter, let’s create a checkbox option that’s off by default, similar to the other checkbox that's there. Otherwise anyone that updates the plugin to the new version will have the voting enabled on their site by default which they might not want.