Expiration support for vulnerability suppressions

### Current Behavior

Currently vulnerabilities can be suppressed but no expiration can be set like in OWASP Dependency-Check.

### Proposed Behavior

Setting a suppression date would be helpful in cases where:
- A patch for a vulnerability doesn't exist yet
- The vulnerability might not be currently be relevant but worth re-checking in the future

### 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