Audit Screen: Display Purl

### Current Behavior:

Vulnerability Auditing is accessible via a project's Audit tab and also via the Component screen (click on Audit mode when viewing Vulnerabilities tab).

The Audit screen does not display the Package URL (Purl) for the Component.

### Proposed Behavior:

When it's available (ie, using BOM upload rather than Dependency-Check), display a component's Purl on the Audit Screen, The Purl field should be copyable, per #350

The utility of displaying Purl on the Audit screen is to make it easier to double-check results using the OSS Index website. For instance, when a False Positive has been removed from OSS Index, this is not reflected in Dependency-Track.