VulnerabilitySeveritiesCount GraphQL API for OWASP 2021 using ES Vulnerability Finder

Issue to track the GraphQL API implementation for OWASP 2021 using the ES Vulnerability finder being implemented in #524099 (closed)

This particular issue is to have VulnerabilitySeveritiesCount GraphQL API for projects and groups, equivalent to project.vulnerabilitySeveritiesCount and group.vulnerabilitySeveritiesCount