This a follow up from PLANET-6454 and the fact that the GDPR Comments plugin in not maintained anymore. This ticket is about implementing one of its functions: opt-in checkbox.

Backend Requirements:

• This should be configurable (enabled by default), in case non-GDPR NROs want to disable it.
• The setting should live under "Planet 4 > Comments" (new section) and being a checkbox.
• Text: "Display Opt-in checkbox"
• Description: "This will display an opt-in checkbox in the Comments form which will be mandatory for submitting the form (GDPR requirement).".

Frontend Requirements:

• The text of the checkbox label should be part of the template and translatable through the Handbook.
• For The label text: "I agree on providing my name, email and content so that my comment can be stored and displayed in the website.".
• It should be unchecked by default and the submit button disabled. Once it's checked the submit button should be activated.

Migration Requirements

• As this will be deployed along with the existing GDPR plugin we need to add a post-deploy script to disable any plugin option to avoid having multiple checkboxes.
• All plugin options are grouped under a gdpr_comments dict. We can add a post-deploy script and use wp option patch to remove the relevant plugin options. If this is released along with PLANET-6466, we can just remove the plugin.

Documentation Requirements

• Coordinate with Community team to update the relevant Handbook page.