[Frontend] Resolvable design discussions

What does this MR do?

This MR allows discussions and pins on a certain design to be marked as Resolved.

• Resolved discussions are moved to the Resolved Comments area of the sidebar;
• Resolved discussion notes are marked with green check label so they could be easily recognized as resolved ones;
• Design pin, associated with a resolved discussion, won't be shown on the design overlay by default but we show it when resolved discussions section is expanded
• Discussions can be resolved/unresolved with note check icon or with a checkbox when adding a new comment to discussion

Screenshots

#13049 (designs)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Issue: #13049 (closed)