Create system notes for design events

What does this MR do?

This MR adds system note support for designs added to issues.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

This MR adds new DB activity to be performed on each design-management action including creation and modification. This will add some overhead to these calls, and increase the query count. At present these are unlikely to be a performance issue, but they may need to be moved to a background worker in the future.

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.