Analyze mobile app usage

Consider a mobile app that sends custom event telemetry. You can

- Count how many distinct users have sent each custom event from your app in the last 24 hours, sorted by these distinct counts
- Analyze conversion, retention, and navigation patterns in your app

One example (this code sample is not ksql-ready, it needs to be adapted):

```
customEvents
| where timestamp >= ago(24h)
| summarize dcount(user_Id) by name
| order by dcount_user_Id desc
```

Inspiration: https://docs.microsoft.com/en-us/azure/azure-monitor/app/mobile-center-quickstart