WIP: Add ability to toggle public visibility of metric dashboard

What does this MR do?

Adds a metrics dashboard visibility toggle inside project -> general section

Issue: #201924 (closed)

Documentation merge request: !29423 (merged)

Screenshots

Visibility Toggle

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content