chore(key-manager): make new keymanager ui default

[andypf]

Summary

This PR updates the application to make the new Key Manager UI the default. The old UI cannot be fully removed yet due to shared functionality in the service layer.

Changes Made

• Updated the Main Navigation to link to the new Key Manager UI.
• Removed the dependency on the assets server.

Related Issues

• [Task](key-manager): remove old plugin and make new default #1461

Screenshots (if applicable)

Checklist

• I have performed a self-review of my code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have made corresponding changes to the documentation (if applicable).
• My changes generate no new warnings or errors.