Selected model training time / retraining

**Is your feature request related to a problem? Please describe.**
Further training of already selected Trainer is impossible in the wizard. Retraining is unintuitive (have to either go back to Train step, or re-launch the wizard and step through Scenario, Environment, and Data (much less likely to have changed) and then do it on the Train step).

**Describe the solution you'd like**
-Wizard should address selecting the Trainer/algorithm and training with that algorithm separately. Perhaps sequentially. Either way, there should be a configurable amount of time spent trying out and selecting the algorithm, AND a configurable amount of time continuing training using that algorithm. Spending a fixed amount of time to try out different algorithms and also train on the data is unintuitive and inefficient
-If not / perhaps regardless, then the Next Steps should have an option to further train the model (it should also have a button to close the wizard, it's not intuitive that you're done and can/should just close the whole tab that the wizard is in)
-Consume should show to programmatically do additional training, with or without additional data

**Describe alternatives you've considered**
Exploring the API and programmatically doing more training.

Inizia esaminando i flussi Train e Next Steps del wizard, quindi analizza le indicazioni di Consume e l'esplorazione dell'API menzionate nell'issue. Il lavoro è completato quando gli utenti possono riaddestrare un algoritmo selezionato senza ripetere la configurazione invariata, possono terminare o continuare chiaramente da Next Steps e possono trovare indicazioni per un ulteriore addestramento con o senza altri dati.

Scritto dal modello di indicizzazione a partire dal testo della issue.