Track usage with Datadog RUM

Replace Google analytics with Datadog RUM

See https://www.datadoghq.com/rum/ for a description
Follow the setup guide: https://docs.datadoghq.com/real_user_monitoring/installation/?tab=us
Make sure to include information about logged in users, for example
```javascript
datadogRum.addRumGlobalContext('usr', { // usr as defined in the datadog naming guide https://docs.datadoghq.com/logs/processing/attributes_naming_convention/#user-related-attributes
uid: username,
groups: groups // If available
});
```

Reach out to an RTP for client and application tokens

Start by locating the existing Google Analytics integration, then follow the linked Datadog RUM installation guide. Confirm how client and application tokens are obtained from an RTP and how logged-in user data is available; done means Google Analytics is replaced, RUM is configured, and the specified user context is included where available.

Written by the indexing model from the issue text.