Summarise scheduled jobs on the dashboard

Scheduled jobs push everything else on the dashboard down, which makes
them very prominent. This is exacerbated by people scheduling more jobs
simultaneously than we expected when we originally designed the feature.

We also want to remove all jobs from the dashboard, in favour of putting
them on the uploads page.

So this commit replaces them with one of our new dashboard banners (used
for received text messages in returned letters) which summarises:
- how many scheduled jobs you have
- when the first one is going out (i.e. how long you have to stop it, if
  you need to)

tests/app/main/views/test_dashboard.py

@@ -227,7 +227,7 @@ def test_inbound_messages_shows_count_of_messages_when_there_are_messages(
         'main.service_dashboard',
         service_id=SERVICE_ONE_ID,
     )
-    banner = page.select_one('a.banner-dashboard')
+    banner = page.select('a.banner-dashboard')[1]
     assert normalize_spaces(
         banner.text
     ) == '9,999 text messages received latest message just now'
@@ -254,7 +254,7 @@ def test_inbound_messages_shows_count_of_messages_when_there_are_no_messages(
         'main.service_dashboard',
         service_id=SERVICE_ONE_ID,
     )
-    banner = page.select_one('a.banner-dashboard')
+    banner = page.select('a.banner-dashboard')[1]
     assert normalize_spaces(banner.text) == '0 text messages received'
     assert banner['href'] == url_for(
         'main.inbox', service_id=SERVICE_ONE_ID
@@ -625,7 +625,7 @@ def test_should_show_recent_templates_on_dashboard(
     headers = [header.text.strip() for header in page.find_all('h2') + page.find_all('h1')]
     assert 'In the last 7 days' in headers
 
-    table_rows = page.find_all('tbody')[1].find_all('tr')
+    table_rows = page.find_all('tbody')[0].find_all('tr')
 
     assert len(table_rows) == 4
 
@@ -825,20 +825,26 @@ def test_should_show_upcoming_jobs_on_dashboard(
         'main.service_dashboard',
         service_id=SERVICE_ONE_ID,
     )
-
     second_call = mock_get_jobs.call_args_list[1]
     assert second_call[0] == (SERVICE_ONE_ID,)
     assert second_call[1]['statuses'] == ['scheduled']
 
-    table_rows = page.find_all('tbody')[0].find_all('tr')
-    assert len(table_rows) == 2
+    assert normalize_spaces(
+        page.select_one('main h2').text
+    ) == (
+        'In the next few days'
+    )
 
-    assert 'send_me_later.csv' in table_rows[0].find_all('th')[0].text
-    assert 'Sending today at 11:09am' in table_rows[0].find_all('th')[0].text
-    assert table_rows[0].find_all('td')[0].text.strip() == '1'
-    assert 'even_later.csv' in table_rows[1].find_all('th')[0].text
-    assert 'Sending today at 11:09pm' in table_rows[1].find_all('th')[0].text
-    assert table_rows[1].find_all('td')[0].text.strip() == '1'
+    assert normalize_spaces(
+        page.select_one('a.banner-dashboard').text
+    ) == (
+        '2 files waiting to send '
+        'sending starts today at 11:09am'
+    )
+
+    assert page.select_one('a.banner-dashboard')['href'] == url_for(
+        'main.uploads', service_id=SERVICE_ONE_ID
+    )
 
 
 @pytest.mark.parametrize('permissions', (
@@ -919,7 +925,7 @@ def test_should_show_recent_jobs_on_dashboard(
     assert third_call[1]['limit_days'] == 7
     assert 'scheduled' not in third_call[1]['statuses']
 
-    table_rows = page.find_all('tbody')[1].find_all('tr')
+    table_rows = page.select_one('tbody').select('tr')
 
     assert len(table_rows) == 4
 
@@ -1151,6 +1157,7 @@ def test_menu_send_messages_when_service_does_not_have_upload_letters_permission
     mock_get_usage,
     mock_get_inbound_sms_summary,
     mock_get_free_sms_fragment_limit,
+    mock_get_returned_letter_summary_with_no_returned_letters,
 ):
     with app_.test_request_context():
         resp = _test_dashboard_menu(
@@ -1159,8 +1166,9 @@ def test_menu_send_messages_when_service_does_not_have_upload_letters_permission
             api_user_active,
             service_one,
             ['view_activity', 'send_messages'])
-        page = resp.get_data(as_text=True)
-        assert url_for('main.uploads', service_id=service_one['id']) not in page
+        page = BeautifulSoup(resp.data.decode('utf-8'), 'html.parser')
+        assert page.select_one('.navigation')
+        assert url_for('main.uploads', service_id=service_one['id']) not in page.select_one('.navigation')
 
 
 def test_menu_manage_service(