home: Get default_language info from cookie for spectator.

This allows us to set default_language as cookie in frontend which
can be used on server load to send the relevant
translation data to the client.

zerver/lib/home.py

@@ -163,14 +163,16 @@ def build_page_params_for_home_page_load(
         }
         default_language = realm.default_language
 
+    if user_profile is None:
+        request_language = request.COOKIES.get(settings.LANGUAGE_COOKIE_NAME, default_language)
+    else:
+        request_language = get_and_set_request_language(
+            request,
+            default_language,
+            translation.get_language_from_path(request.path_info),
+        )
+
     furthest_read_time = get_furthest_read_time(user_profile)
-
-    request_language = get_and_set_request_language(
-        request,
-        default_language,
-        translation.get_language_from_path(request.path_info),
-    )
-
     two_fa_enabled = settings.TWO_FACTOR_AUTHENTICATION_ENABLED and user_profile is not None
     billing_info = get_billing_info(user_profile)
     user_permission_info = get_user_permission_info(user_profile)
@@ -234,5 +236,6 @@ def build_page_params_for_home_page_load(
         # Get rendered version of realm description which is displayed in right
         # sidebar for spectator.
         page_params["realm_rendered_description"] = get_realm_rendered_description(realm)
+        page_params["language_cookie_name"] = settings.LANGUAGE_COOKIE_NAME
 
     return register_ret["queue_id"], page_params

zerver/tests/test_home.py

@@ -338,6 +338,7 @@ class HomeTest(ZulipTestCase):
             "furthest_read_time",
             "insecure_desktop_app",
             "is_spectator",
+            "language_cookie_name",
             "language_list",
             "login_page",
             "needs_tutorial",