[Enhancement]: Improved DAB CLI appinsights config usage

### What happened?

Improved experience with adding telemetry config via CLI:

1. `add-telemetry` -> indicates you'd be adding new telemetry sections each time. Unclear that you need to use this for "update" as well. What about "delete?

2. `--app-insights-enabled` option can't be used on its own, always needs a connection string. This makes sense if all you're doing is "adding" but doesn't make sense for "update".

### Version

.11rc

### What database are you using?

Azure SQL

### What hosting model are you using?

Local (including CLI)

### Which API approach are you accessing DAB through?

REST

### Relevant log output

_No response_

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct

Aucun fichier, test ou point d’entrée n’est nommé. Commencez par localiser la configuration de télémétrie de DAB CLI et le traitement des options App Insights, puis clarifiez le comportement prévu pour l’ajout, la mise à jour et la suppression ; la tâche devrait être considérée comme terminée lorsque la CLI prend en charge les opérations convenues sans nécessiter de connection string inutile.

Rédigé par le modèle d'indexation à partir du texte de l'issue.