Show active alerts for integrations

[balloob]

We should include the alerts from https://alerts.home-assistant.io/

If there are integrations with alerts, we should show them on the integrations tab.

The data is available at https://alerts.home-assistant.io/alerts.json

[spacegaier]

In addition to the info on the integrations page, wouldn't a notification also make sense to notify the user of the alert, without having to manually check the integrations page?