Add missing report-uri to CSP config

This is supported in Rails 5.2, although it may be
deprecated in the future by reports-to.

changelogs/unreleased/sh-add-missing-csp-report-uri.yml

+---
+title: Add missing report-uri to CSP config
+merge_request: 31593
+author:
+type: fixed

lib/gitlab/content_security_policy/config_loader.rb

@@ -5,7 +5,7 @@ module Gitlab
     class ConfigLoader
       DIRECTIVES = %w(base_uri child_src connect_src default_src font_src
                       form_action frame_ancestors frame_src img_src manifest_src
-                      media_src object_src script_src style_src worker_src).freeze
+                      media_src object_src report_uri script_src style_src worker_src).freeze
 
       def self.default_settings_hash
         {

spec/lib/gitlab/content_security_policy/config_loader_spec.rb

@@ -13,7 +13,8 @@ describe Gitlab::ContentSecurityPolicy::ConfigLoader do
         child_src: "'self' https://child.example.com",
         default_src: "'self' https://other.example.com",
         script_src: "'self'  https://script.exammple.com ",
-        worker_src: "data:  https://worker.example.com"
+        worker_src: "data:  https://worker.example.com",
+        report_uri: "http://example.com"
       }
     }
   end
@@ -46,6 +47,7 @@ describe Gitlab::ContentSecurityPolicy::ConfigLoader do
       expect(policy.directives['default-src']).to eq(expected_config(:default_src))
       expect(policy.directives['child-src']).to eq(expected_config(:child_src))
       expect(policy.directives['worker-src']).to eq(expected_config(:worker_src))
+      expect(policy.directives['report-uri']).to eq(expected_config(:report_uri))
     end
 
     it 'ignores malformed policy statements' do