Vulnerability Report: Add identifier list popover
### Summary
We have the identifiers in the GraphQL response on the Vulnerability Report. When there is more than 1, we simply show "+ x more". Similar to the risk factors, we should show these extra identifiers in a popover.
### Design
| | Severity: +N more | Identifier: +N more |
|--|-------------------|---------------------|
| Default (no hover or focus) |  |  |
| Cursor hover |  |  |
| Tab (focus state) |  |  |
### Implementation
1. Create identifier popover
2. Make sure we use [meta link style](https://design-gitlab-com-gitlab-org-gitlab-services-f6beaf2fb7fd4cad76.gitlab.io/storybook/?path=%2Fstory%2Fbase-link--meta-link) for both the "+x more" on the identifier as well as the risk factors, so this is consistent
### Release notes
The Vulnerability Report now shows the primary CVE identifier as a clickable link directly in each row. When additional identifiers exist, a **"+N more"** popover lists them all — each linking to its external reference (e.g., CVE, CWE, WASC databases) so you can quickly access more details without leaving the report.
See [#564939](https://gitlab.com/gitlab-org/gitlab/-/work_items/564939) for details.
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