Edited VulnerabilityCard Severity Level Formatting (CRASM-1056)

[hawkishpolicy]

• Added formatting of severity levels that match Vulnerability Bar Graph to the VulnerabilityCard component.
• This resolves formatting issues for both the Latest Vulnerabilities and Most Common Vulnerabilities cards in Risk.

• All severity levels are title case.
• Null, N/A, undefined, and empty strings are now displayed as "N/A".
• Any severity level that is not "Critical", "High", "Medium", "Low", or "N/A" is displayed as "Other".

🗣 Description

💭 Motivation and context

• Provides formatting of irregular severity levels.
• Closes CRASM-1056

🧪 Testing

• tested locally

📷 Screenshots (if appropriate)

✅ Pre-approval checklist

• This PR has an informative and human-readable title.
• Changes are limited to a single goal - eschew scope creep!
• All relevant type-of-change labels have been added.
• I have read the CONTRIBUTING document.
• These code changes follow cisagov code standards.
• All new and existing tests pass.

✅ Pre-merge checklist

• Revert dependencies to default branches.
• Finalize version.

✅ Post-merge checklist

• Create a release.