Add multiple ‘edit’ links for letter templates

Letter templates have (or will have) multiple different editable
regions. I think that the most intuitive way for this to work is to have
- an edit link for each of these areas
- positioned next to the thing to be edited

Again, this isn’t fully hooked up, but since no-one is using letters
live yet this is a good way of getting research feedback and pointing
towards where we want the feature to go.

Uses percentages for the positioning so that the alignment is maintained
on mobile.

tests/app/main/views/test_templates.py

@@ -564,10 +564,11 @@ def test_should_show_page_for_a_deleted_template(
     assert response.status_code == 200
 
     content = response.get_data(as_text=True)
+    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
     assert url_for("main.edit_service_template", service_id=fake_uuid, template_id=fake_uuid) not in content
     assert url_for("main.send_from_api", service_id=fake_uuid, template_id=fake_uuid) not in content
     assert url_for("main.send_test", service_id=fake_uuid, template_id=fake_uuid) not in content
-    assert "This template was deleted<br/>1 January 2016" in content
+    assert page.select('p.hint')[0].text.strip() == 'This template was deleted today at 3:00pm.'
 
     mock_get_deleted_template.assert_called_with(service_id, template_id)