Add sent notifications page for caseworkers

The other task that caseworkers have to do (much less often than sending
messages) is look at the messages which they’ve sent. The reason for
doing this is usually to find a specific message which someone has
complained about.

This commit adds:
- a page where they can do that
- a navigation item so they can get to that page

We reckon that because this is about finding specific messages, not
reporting that it’s fine to mush all the channels (email, text, letter)
into one table.

tests/app/main/views/test_activity.py

@@ -10,11 +10,17 @@ from freezegun import freeze_time
 from app.main.views.jobs import get_status_filters, get_time_left
 from tests.conftest import (
     SERVICE_ONE_ID,
+    active_caseworking_user,
+    active_user_view_permissions,
     mock_get_notifications,
     normalize_spaces,
 )
 
 
+@pytest.mark.parametrize('user', (
+    active_user_view_permissions,
+    active_caseworking_user,
+))
 @pytest.mark.parametrize(
     "message_type,page_title", [
         ('email', 'Emails'),
@@ -72,7 +78,11 @@ def test_can_show_notifications(
     expected_page_argument,
     to_argument,
     expected_to_argument,
+    mocker,
+    user,
+    fake_uuid,
 ):
+    mocker.patch('app.user_api_client.get_user', return_value=user(fake_uuid))
     if expected_to_argument:
         response = logged_in_client.post(
             url_for(

tests/app/test_navigation.py

@@ -159,5 +159,5 @@ def test_caseworkers_get_caseworking_navigation(
     )
     page = client_request.get('main.choose_template', service_id=SERVICE_ONE_ID)
     assert normalize_spaces(page.select_one('#content nav').text) == (
-        'Send a message'
+        'Send a message Sent messages'
     )