Maintain audit trail for any update in an audit vulnerability

### Current Behavior

Currently, for any audit vulnerability in a project if there is any update in analysis say, severity level for a vulnerability, there is no update information documented in its audit trail.

### Proposed Behavior

The information on any update on the vulnerability in a project should be documented to give more visibility over its changes.

### Checklist

- [X] I have read and understand the [contributing guidelines](https://github.com/DependencyTrack/dependency-track/blob/master/CONTRIBUTING.md#filing-issues)
- [X] I have checked the [existing issues](https://github.com/DependencyTrack/dependency-track/issues) for whether this enhancement was already requested