Add fields to `PipelineSecurityReportFinding` GraphQL type

Based on this spike #348282 (closed) we propose to add the fields captured in the schema below to the PipelineSecurityReportFinding:

  extend type PipelineSecurityReportFinding {
    descriptionHtml: String!
  }

This will make sure that the GraphQL API returns all the data that is currently showing within the pipeline finding's modal.

Implementation Plan

• backend Add description_html to PipelineSecurityReportFinding
  • Use https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/app/graphql/types/vulnerability_type.rb as an example.

Verification

To verify this issue, use a GraphQL query to confirm that the descriptionHtml field is available:

query {
  project(fullPath:"<project path>") {
    pipeline(iid:"<pipeline iid>") {
      securityReportFindings(first:1) {
        nodes {
          reportType
          descriptionHtml
        }
      }
    }
  }
}