Allow for resolving comment threads on Wiki pages

Summary

Currently, comment threads on Wiki pages remain open indefinitely, which creates clutter and makes it difficult to track which discussions are active vs. resolved. We need to implement a feature that allows users to mark comment threads as resolved, similar to the functionality available on comments in the rest of GitLab.

Background

Wiki pages are collaborative by nature, and discussions through comments are an essential part of the collaboration process. However, as discussions conclude and decisions are made, there's no way to indicate that a particular comment thread has been addressed. This leads to:

• Cluttered comment sections with a mix of active and inactive discussions
• Difficulty identifying which comments still require attention
• Reduced efficiency when reviewing page history and discussions

Requirements

Functional Requirements

• Add a "Resolve " button/option for each comment thread on Wiki pages
• Include visual indication of resolved threads (e.g., greyed out, collapsed by default)
• Allow reopening of previously resolved threads if further discussion is needed