Adding ical link support for importing calendars

[seb-mm]

I use multiple devices and have multiple sources for my tasks.
One is from my Uni, another one is from Google (everything I add from my phone), and another one for online language classes.

This issue is somewhat like #10 because it would be a week planner. I currently do my task management in Sorted3.

I'm not even sure if Obsidian is the best tool for this approach because doing this in Markdown for weeks/months doesn't seem that intuitive. I imagine it would create a bunch of files, whereas in Sorted 3 I can import the different calendars, create new tasks and drag them to another day.

Now that I've written that out, I think making this plugin into a week planner doesn't make sense.