Include uuid in vulnerability_finding response

Adds uuid field to the finding_entity so that the uuid is in the
vulnerability_finding endpoint responses

doc/api/vulnerability_findings.md

@@ -99,6 +99,7 @@ Example response:
       }
     ],
     "project_fingerprint": "fa6f5b6c5d240b834ac5e901dc69f9484cef89ec",
+    "uuid": "31f483bc-bfc0-586d-9b92-f1015c4535b8",
     "create_vulnerability_feedback_issue_path": "/tests/yarn-remediation-test/vulnerability_feedback",
     "create_vulnerability_feedback_merge_request_path": "/tests/yarn-remediation-test/vulnerability_feedback",
     "create_vulnerability_feedback_dismissal_path": "/tests/yarn-remediation-test/vulnerability_feedback",

ee/app/serializers/vulnerabilities/finding_entity.rb

@@ -8,6 +8,7 @@ class Vulnerabilities::FindingEntity < Grape::Entity
   expose :scanner, using: Vulnerabilities::ScannerEntity
   expose :identifiers, using: Vulnerabilities::IdentifierEntity
   expose :project_fingerprint
+  expose :uuid
   expose :create_jira_issue_url do |occurrence|
     create_jira_issue_url_for(occurrence)
   end

ee/changelogs/unreleased/277128-return-the-uuid-attribute-of-the-finding-records-in-the-respons.yml

+---
+title: Return the uuid attribute in the response of vulnerability_finding endpoint
+merge_request: 49742
+author:
+type: changed

ee/spec/fixtures/api/schemas/vulnerabilities/finding.json

@@ -13,6 +13,7 @@
   "properties" : {
     "name" : { "type": "string" },
     "project_fingerprint": { "type": "string" },
+    "uuid": { "type": ["string", "null"] },
     "create_vulnerability_feedback_issue_path": { "type": "string" },
     "create_vulnerability_feedback_merge_request_path": { "type": "string" },
     "create_vulnerability_feedback_dismissal_path": { "type": "string" },

ee/spec/serializers/vulnerabilities/finding_entity_spec.rb

@@ -59,6 +59,7 @@ RSpec.describe Vulnerabilities::FindingEntity do
       expect(subject).to include(:blob_path, :request, :response)
       expect(subject).to include(:scan)
       expect(subject).to include(:assets, :evidence_source, :supporting_messages)
+      expect(subject).to include(:uuid)
     end
 
     context 'when not allowed to admin vulnerability feedback' do