Allow automatic, recurring import of annotations via ical (or similar formats)

[tsteur]

Use case:

I want to import one or multiple calendars. Specifically, for example "public holiday" calendars. This is helpful when there's for example a public holiday on Friday, and you wonder why the stats are down a certain percentage. By linking calendars this way you can directly look at the annotations and understand what a reason could be.

It can be also useful to automatically import events etc and then you can better understand the analytics data.

I'd basically want to define a URL, and Matomo then automatically creates regularly the annotations for every new event. Not just as a one off but also keeps adding events when new events come up.