Stop saying "areas" when we mean "area_ids"

"areas" normally means an instance of BroadcastArea or similar, so
we should be more accurate to avoid confusion.

tests/__init__.py

@@ -678,7 +678,7 @@ def broadcast_message_json(
     updated_at=None,
     approved_by_id=None,
     cancelled_by_id=None,
-    areas=None,
+    area_ids=None,
     simple_polygons=None,
     content=None,
     reference=None,
@@ -696,7 +696,7 @@ def broadcast_message_json(
         'reference': reference,
 
         'personalisation': {},
-        'areas': areas or [
+        'areas': area_ids or [
             'ctry19-E92000001', 'ctry19-S92000003',
         ],
         'simple_polygons': simple_polygons or [],

tests/app/main/views/test_broadcast.py

@@ -904,7 +904,7 @@ def test_preview_broadcast_areas_page(
             created_by_id=fake_uuid,
             service_id=SERVICE_ONE_ID,
             status='draft',
-            areas=areas_selected,
+            area_ids=areas_selected,
         ),
     )
     client_request.login(active_user_create_broadcasts_permission)
@@ -974,7 +974,7 @@ def test_preview_broadcast_areas_page_with_custom_polygons(
             created_by_id=fake_uuid,
             service_id=SERVICE_ONE_ID,
             status='draft',
-            areas=['Area one', 'Area two', 'Area three'],
+            area_ids=['Area one', 'Area two', 'Area three'],
             simple_polygons=polygons,
         ),
     )
@@ -1000,7 +1000,7 @@ def test_preview_broadcast_areas_page_with_custom_polygons(
     ] == expected_list_items
 
 
-@pytest.mark.parametrize('areas, expected_list', (
+@pytest.mark.parametrize('area_ids, expected_list', (
     ([], [
         'Countries',
         'Demo areas',
@@ -1053,7 +1053,7 @@ def test_choose_broadcast_library_page(
     service_one,
     fake_uuid,
     active_user_create_broadcasts_permission,
-    areas,
+    area_ids,
     expected_list,
 ):
     service_one['permissions'] += ['broadcast']
@@ -1065,7 +1065,7 @@ def test_choose_broadcast_library_page(
             created_by_id=fake_uuid,
             service_id=SERVICE_ONE_ID,
             status='draft',
-            areas=areas,
+            area_ids=area_ids,
         ),
     )
     client_request.login(active_user_create_broadcasts_permission)
@@ -1108,7 +1108,7 @@ def test_suggested_area_has_correct_link(
             created_by_id=fake_uuid,
             service_id=SERVICE_ONE_ID,
             status='draft',
-            areas=[
+            area_ids=[
                 'wd20-E05004299',  # Pitville, a ward of Cheltenham
             ],
         ),

tests/app/models/test_broadcast_message.py

@@ -11,7 +11,7 @@ def test_simple_polygons(fake_uuid):
         template_id=fake_uuid,
         status='draft',
         created_by_id=fake_uuid,
-        areas=[
+        area_ids=[
             # Hackney Central
             'wd20-E05009372',
             # Hackney Wick
@@ -56,7 +56,7 @@ def test_raises_for_missing_areas(fake_uuid):
         template_id=fake_uuid,
         status='draft',
         created_by_id=fake_uuid,
-        areas=[
+        area_ids=[
             'wd20-E05009372',
             'something else',
         ],