Add NVD CVE alias to issues reported through Snyk

### Current Behavior

Issues imported from Github with a Github vulnerability ID contain a proper alias to link the Github identifier to the NVD CVE identifier.
For Snyk vulnerabilities with a Snyk identifier, there is no such alias even though it usually exists.
For example:

- Snyk vulnerability: https://security.snyk.io/vuln/SNYK-JAVA-ORGAPACHELOGGINGLOG4J-17954276
- Snyk identifier: SNYK-JAVA-ORGAPACHELOGGINGLOG4J-17954276
- Contains a reference to NVD CVE CVE-2026-49844

But the NVD CVE alias is not populated in the Snyk vulnerability in DependencyTrack:
https://dependencytrack/vulnerabilities/SNYK/SNYK-JAVA-ORGAPACHELOGGINGLOG4J-17954276

### Proposed Behavior

Add the NVD CVE identifier as an alias to the Snyk vulnerability

### Checklist

- [x] I have read and understand the [contributing guidelines](https://github.com/DependencyTrack/dependency-track/blob/main/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

Trace the Snyk vulnerability import handling and compare it with the existing GitHub vulnerability alias behavior. Use the Snyk example SNYK-JAVA-ORGAPACHELOGGINGLOG4J-17954276 and verify that CVE-2026-49844 appears as an alias on the resulting vulnerability.

Written by the indexing model from the issue text.