Add top-level vulnerability field for GraphQL API

Add vulnerability field to load data for single vulnerability record.

doc/api/graphql/reference/gitlab_schema.graphql

@@ -14271,6 +14271,16 @@ type Query {
     """
     startDate: ISO8601Date!
   ): VulnerabilitiesCountByDayAndSeverityConnection @deprecated(reason: "Use `vulnerabilitiesCountByDay`. Deprecated in 13.3")
+
+  """
+  Find a vulnerability
+  """
+  vulnerability(
+    """
+    The Global ID of the Vulnerability
+    """
+    id: VulnerabilityID!
+  ): Vulnerability
 }
 
 """

doc/api/graphql/reference/gitlab_schema.json

@@ -41743,6 +41743,33 @@
               },
               "isDeprecated": true,
               "deprecationReason": "Use `vulnerabilitiesCountByDay`. Deprecated in 13.3"
+            },
+            {
+              "name": "vulnerability",
+              "description": "Find a vulnerability",
+              "args": [
+                {
+                  "name": "id",
+                  "description": "The Global ID of the Vulnerability",
+                  "type": {
+                    "kind": "NON_NULL",
+                    "name": null,
+                    "ofType": {
+                      "kind": "SCALAR",
+                      "name": "VulnerabilityID",
+                      "ofType": null
+                    }
+                  },
+                  "defaultValue": null
+                }
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "Vulnerability",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
             }
           ],
           "inputFields": null,

ee/app/graphql/ee/types/query_type.rb

@@ -21,6 +21,16 @@ module EE
               description: "Vulnerabilities reported on projects on the current user's instance security dashboard",
               resolver: ::Resolvers::VulnerabilitiesResolver
 
+        field :vulnerability,
+              ::Types::VulnerabilityType,
+              null: true,
+              description: "Find a vulnerability",
+              resolve: -> (_obj, args, _ctx) { ::GitlabSchema.find_by_gid(args[:id]) } do
+          argument :id, ::Types::GlobalIDType[::Vulnerability],
+                   required: true,
+                   description: 'The Global ID of the Vulnerability'
+        end
+
         field :vulnerabilities_count_by_day,
               ::Types::VulnerabilitiesCountByDayType.connection_type,
               null: true,

ee/changelogs/unreleased/223813_implement_vulnerability_graphql_query.yml

+---
+title: Introduce top-level `vulnerability` field for GraphQL API
+merge_request: 42870
+author:
+type: added

ee/spec/graphql/types/query_type_spec.rb

@@ -8,6 +8,7 @@ RSpec.describe GitlabSchema.types['Query'] do
       :iteration,
       :geo_node,
       :vulnerabilities,
+      :vulnerability,
       :instance_security_dashboard,
       :vulnerabilities_count_by_day_and_severity
     ).at_least