Add web UI notification for under voltage/throttling events (#1203)

python/web/tests/api/test_settings.py

@@ -286,3 +286,12 @@ def test_rename_system(env, http_client):
     response_data = response.json()
 
     assert response_data["data"]["system_name"] == old_name
+
+
+def test_throttle_notification(http_client):
+    response = http_client.get("/")
+    response_data = response.json()
+
+    assert response.status_code == 200
+    assert response_data["status"] == STATUS_SUCCESS
+    assert "Under voltage detected" in response_data["data"]