Modify offline mode to include caching on server connection failure

This will likely require a complete refactor of offline mode. We want to now include caching of objects such that if a connection cannot be made to the server, these objects are uploaded at a later time. This can be merged with the offline mode concept, the difference being offline mode would be clearly stating that connection to a server is not possible, whereas a typical run would keep re-trying to upload the runs at a given interval.

This could be merged with the concept of having object orientation for Simvue objects and their storage locally.

No se nombran archivos ni pruebas. Empieza por localizar la implementación existente del modo sin conexión y la ruta de almacenamiento de objetos de Simvue; después, sigue el flujo de cómo se cargan los runs y cómo se gestionan los fallos de conexión. Se considera terminado cuando las conexiones fallidas almacenan en caché los objetos para cargarlos más tarde, reintentan en un intervalo definido y distinguen los reintentos normales del modo sin conexión activado explícitamente.