Add `sort` parameter to `securityReportFindings` GraphQL query

In order to support the sorting of pipeline findings, we need to add a sort functionality to the securityReportFindings query.

Suggestion: we use the same approach that we currently use for the vulnerability reports and add a sort parameter (with the same possible values as VulnerabilitySort) to the securityReportFindings query.

Implementation plan:

• Add sort parameter PipelineSecurityReportFindingsResolver
• Add the ability to sort in Security::PureFindingsFinder
• Try to use VulnerabilitySortEnum and follow the same pattern as VulnerabilitiesResolver sort argument