Preload project features in reference parser

Preloading of project_features mitigates N+1 queries when checking
references in other projects.

When loading projects for resources referenced in comments it
makes sense to include also associated project_features because
in the following step (`can_read_reference?(user, projects[node],
node)`) project features is used for checking permissions for the given
project.

changelogs/unreleased/load_project_features.yml

@@ -0,0 +1,5 @@
+---
+title: Mitigate N+1 queries when parsing commit references in comments.
+merge_request:
+author:
+type: performance

lib/banzai/reference_parser/base_parser.rb

@@ -215,7 +215,7 @@ module Banzai
       #
       def projects_for_nodes(nodes)
         @projects_for_nodes ||=
-          grouped_objects_for_nodes(nodes, Project, 'data-project')
+          grouped_objects_for_nodes(nodes, Project.includes(:project_feature), 'data-project')
       end
 
       def can?(user, permission, subject = :global)

spec/lib/banzai/reference_parser/commit_parser_spec.rb

@@ -120,4 +120,22 @@ describe Banzai::ReferenceParser::CommitParser do
       expect(subject.find_commits(project, %w{123})).to eq([])
     end
   end
+
+  context 'when checking commits on another projects' do
+    let(:control_links) do
+      [commit_link]
+    end
+
+    let(:actual_links) do
+      control_links + [commit_link, commit_link]
+    end
+
+    def commit_link
+      project = create(:project, :repository, :public)
+
+      Nokogiri::HTML.fragment(%Q{<a data-commit="#{project.commit.id}" data-project="#{project.id}"></a>}).children[0]
+    end
+
+    it_behaves_like 'no project N+1 queries'
+  end
 end

spec/support/helpers/reference_parser_helpers.rb

@@ -3,7 +3,7 @@ module ReferenceParserHelpers
     Nokogiri::HTML.fragment('<a></a>').children[0]
   end
 
-  shared_examples 'no N+1 queries' do
+  shared_examples 'no project N+1 queries' do
     it 'avoids N+1 queries in #nodes_visible_to_user', :request_store do
       context = Banzai::RenderContext.new(project, user)
 
@@ -19,6 +19,10 @@ module ReferenceParserHelpers
       expect(actual.count).to be <= control.count
       expect(actual.cached_count).to be <= control.cached_count
     end
+  end
+
+  shared_examples 'no N+1 queries' do
+    it_behaves_like 'no project N+1 queries'
 
     it 'avoids N+1 queries in #records_for_nodes', :request_store do
       context = Banzai::RenderContext.new(project, user)