Add open and click rates to emails from Dashboards Subscriptions and Alerts

**Is your feature request related to a problem? Please describe.**
With the new Metabase Analytics Collection in 48, you can easily see which emails were sent from Dashboard Subscriptions and Alerts.
Maybe this is crazy, but it would be awesome if we could measure click rates and open rates from those emails and show that data in the auditing collection.

**Describe the solution you'd like**
Collect logs to extract metrics and broadcast them in Metabase Analytics

**Describe alternatives you've considered**
N/A

**How important is this feature to you?**
Often happens to Cloud instances that can't manage their own SMTP servers as we manage it for them.

**Additional context**
Add any other context or screenshots about the feature request here.

Start by locating the Dashboard Subscriptions and Alerts email-delivery flow and the Metabase Analytics Collection or auditing collection. Clarify how open and click events can be collected, then define the reporting requirements; done means both rates are available for those emails in the analytics collection.

Written by the indexing model from the issue text.