fix: Migrate notes when merging the contacts (#8749)

Fixes: https://linear.app/chatwoot/issue/CW-2987/migrate-notes-of-the-secondary-contact-to-primary-contact-when-merging

spec/actions/contact_merge_action_spec.rb

@@ -18,6 +18,7 @@ describe ContactMergeAction do
       create(:conversation, contact: base_contact)
       create(:conversation, contact: mergee_contact)
       create(:message, sender: mergee_contact)
+      create(:note, contact: mergee_contact, account: mergee_contact.account)
     end
   end
 
@@ -68,6 +69,17 @@ describe ContactMergeAction do
       end
     end
 
+    context 'when mergee contact has notes' do
+      it 'moves the notes to base contact' do
+        expect(base_contact.notes.count).to be 0
+        expect(mergee_contact.notes.count).to be 2
+
+        contact_merge
+
+        expect(base_contact.reload.notes.count).to be 2
+      end
+    end
+
     context 'when contacts belong to a different account' do
       it 'throws an exception' do
         new_account = create(:account)