Severity Level Validation Improvements (CRASM-1057)

[hawkishpolicy]

• Refined and uniformed the grouping and sorting logic of irregular severity levels in the Vulns Bar Chart and All Vulns Table components.

🗣 Description

• None, null, n/a, undefined, empty strings, and stringified versions of None, Null, N/A, and undefined are now grouped into the N/A category in both the Vulns Bar Chart and All Vulns table.
• Both components now force Title Case on the severity level strings first then sort and group into their respective categories.
• Edited the comparator function in the All Vulns tables to sort the severity levels in the correct order from N/A, Low, Medium, High, Critical, Other.
• Edited the apply_vuln_filters function in filter_helpers.py to return all vulns that meet the requirements for N/A and Other values.
• Edited the get_stats_count_from_cache function to so that null values returned from the Redis call receive an id of "None" and a value of 1 to ensure proper incrementing.
• Edited sync_db helpers to populate sample vulnerabilities with numerous irregular severity levels.
• Edited search_vulnerabilities function so that Regional Admins can only view vulnerabilities in their region.
• Edited Vulns table to no longer pass in a user's current organization unless they were a Standard user.
• Edited get_stats_org_ids to allow Standard users to pass in their org id into the stats call.
  • This was causing a 403 error and requiring standard users to refresh the Overview page after returning to it.

💭 Motivation and context

• Improves sorting and grouping of irregular severity levels.
• Closes CRASM-1057

🧪 Testing

• Seeded local DB with irregular values.

📷 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.