Display SHA fingerprint for Deploy Keys and extend api to query those

What does this MR do?

This MR displays the SSH SHA256 fingerprints for Deploy keys #119209 (closed) . It is a follow-up from !19860 (merged) . Beside of this the api/keys does allow now to query all keys.

Screenshots

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

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