Pinning integration: Solve for "pins" item in File screen info bar

[jessicaschilling]

Note: This issue is part of a larger pinning service integration epic undertaken spring/summer 2020.

In brief

Once pinning services are better integrated into Web UI, the "pins" item in the File screen info bar will benefit considerably from refining — either adding additional explanatory context, or repurposing altogether.

• Discuss best-case UX for this info bar once pinning services have been added
• Determine functional requirements
• Draw up, discuss and agree upon UI instantiation
• Implement as a PR to close this issue, or if it's a substantial enough effort, open and resolve a new issue for implementation

This isn't critical work for MVP release, but is high on a nice-to-have list.