Handle com.unity3d.kharma for web-based Asset Store integration?

This may be a duplicate of #67 and #92, but those were closed without any further details.

I want to test using Unity for a project, so I found this [free sample project](https://assetstore.unity.com/packages/essentials/tutorial-projects/dragon-crashers-2d-sample-project-190721) on Unity's web-based Asset Store. After adding it to my account, there's a button to "Open in Unity". When I hit that, I'm presented with an "Open With..." dialog because the `com.unity3d.kharma` scheme is unhandled:

Unfortunately when trying to manually set this up in a .desktop file, the Hub opened but the asset did not, so it's possible this would need to be fixed within the hub code itself.

Inizia riproducendo l’azione "Open in Unity" dell’Asset Store web di Unity e ispeziona la gestione del file .desktop per lo schema com.unity3d.kharma. Poi determina se la modifica appartiene all’integrazione desktop o direttamente al codice dell’Hub. Il lavoro è completato quando l’Hub si apre e il progetto Asset Store selezionato viene importato o aperto, invece di limitarsi ad avviare l’Hub.

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