Provide built-in integration with `strapi-plugin-reactions`

[cyp3rius]

Summary

As that was highlighted in the issue VirtusLab-Open-Source/strapi-plugin-reactions#36 there is no possibility to programmatically extend the controllers of Client API for Comments Plugin to enrich the response by reactions.

Expectations

1. Plugin recognizes if the strapi-reactions-plugin is installed and provides the option in the Settings Page to Enable the integration.
2. When integration is enabled, the controllers for listing comments (flat, tree, rfr) use the enrich service method or use their own implementation to provide rich data
3. When integration is enabled, the interface shows the reactions correlated with each comment using its emoji/image + counter. It's not an interactive element.