Content changes for notification pages

This commit adds content pages for the notifications pages, particularly
the letter pages, which will make things clearer now that we will soon be allowing
letters to be cancelled.

The main changes are:
* The confirmation banner for letters sent from a CSV file now states when
printing will start.
* We state the CSV file that notifications were sent from on the
notifications page
* The notification page for letters shows when printing starts (today,
tomorrow, or that date that the letter was printed)

tests/app/main/views/test_jobs.py

@@ -343,8 +343,8 @@ def test_should_show_letter_job(
     )
 
 
-@freeze_time("2016-01-01 11:09:00.061258")
-def test_should_show_letter_job_with_banner_after_sending(
+@freeze_time("2016-01-01 11:09:00")
+def test_should_show_letter_job_with_banner_after_sending_before_1730(
     client_request,
     mock_get_service_letter_template,
     mock_get_job,
@@ -362,7 +362,30 @@ def test_should_show_letter_job_with_banner_after_sending(
 
     assert page.select('p.bottom-gutter') == []
     assert normalize_spaces(page.select('.banner-default-with-tick')[0].text) == (
-        'We’ve started printing your letters'
+        'Your letter has been sent. Printing starts today at 5.30pm.'
+    )
+
+
+@freeze_time("2016-01-01 18:09:00")
+def test_should_show_letter_job_with_banner_after_sending_after_1730(
+    client_request,
+    mock_get_service_letter_template,
+    mock_get_job,
+    mock_get_notifications,
+    mock_get_service_data_retention_by_notification_type,
+    fake_uuid,
+):
+
+    page = client_request.get(
+        'main.view_job',
+        service_id=SERVICE_ONE_ID,
+        job_id=fake_uuid,
+        just_sent='yes',
+    )
+
+    assert page.select('p.bottom-gutter') == []
+    assert normalize_spaces(page.select('.banner-default-with-tick')[0].text) == (
+        'Your letter has been sent. Printing starts tomorrow at 5.30pm.'
     )