Add editor_id to top-level fields

This ensures this value gets set if it is present. I’ve added some
shared exampes to the new edition and previous draft integration specs,
as these seemed like the best places for them to go.

app/models/edition.rb

@@ -16,6 +16,7 @@ class Edition < ApplicationRecord
     description
     details
     document_type
+    editor_id
     first_published_at
     last_edited_at
     major_published_at

spec/integration/put_content/content_with_a_previous_draft_spec.rb

@@ -52,6 +52,10 @@
     expect(previously_drafted_item.last_edited_at).to eq(Time.zone.now)
   end
 
+  include_examples "setting editor_id" do
+    subject { previously_drafted_item.reload }
+  end
+
   context "when public_updated_at is in the payload" do
     let(:public_updated_at) { Time.zone.now }
     before do

spec/integration/put_content/new_edition_spec.rb

@@ -83,6 +83,8 @@
     include_examples "creates a change note"
   end
 
+  include_examples "setting editor_id"
+
   context "and the change history is in the details hash" do
     before do
       payload.delete(:change_note)

spec/support/shared_context/put_content_calls.rb

@@ -22,4 +22,27 @@
   let(:locale) { "en" }
   let(:content_id) { SecureRandom.uuid }
   let(:change_note) { "change note" }
+
+  shared_examples "setting editor_id" do
+    context "when editor_id is present in the payload" do
+      let(:editor_id) { SecureRandom.uuid }
+      before do
+        payload.merge!(
+          editor_id:,
+        )
+      end
+
+      it "adds an editor_id to the edition" do
+        put "/v2/content/#{content_id}", params: payload.to_json
+
+        expect(subject.editor_id).to eq(editor_id)
+      end
+    end
+
+    it "does not set an editor_id by default" do
+      put "/v2/content/#{content_id}", params: payload.to_json
+
+      expect(subject.editor_id).to be_nil
+    end
+  end
 end