Add Upvote/Downvote Functionality for Comments

[rohnsha0]

Add upvote and downvote buttons to comments to allow users to express approval or disapproval and help surface high-quality content through community feedback with the following features:

• Upvote button (▲) - allows users to express agreement or appreciation
• Downvote button (▼) - allows users to express disagreement or flag low-quality content
• Vote counter - displays net score (upvotes minus downvotes)
• User voting state - visual indication of user's current vote on each comment

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Note: Partial implementation already completed. Some foundational work for this feature has been implemented and is ready for integration/extension.

[davisagli]

There are some existing add-ons which provide a similar feature. They might need updates for Plone 6.

• https://github.com/collective/plone.contentratings
• https://github.com/collective/cioppino.twothumbs