Add metrics dashboard template selector for the WebIDE

What does this MR do?

This adds the metrics-dashboard.yml template selector to the WebIDE

#220178 (closed)

This needs the corresponding backend branch to be merged into master, I'll change the targets once the aforementioned branch is merged

Screenshots

WebIDE file selection modal	WebIDE template dropdown

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