feat: Show ICS events in Calendar widget

[Janbong]

Hi, I saw #174, but it was based on the old Calendar widget.

I did something similar, but using Javascript only, since the new Calendar widget is also Javascript only.

This supports having multiple events on one day, see screenshot. Changing timezone also works.

Multiple ICS files possible as well (only public for now).

Thanks to https://github.com/develoopeer for some snippets I used from his #174 PR

In #174, there is mention of CalDAV support by https://github.com/develoopeer. I'm interested in that as well.

[AWildLeon]

Oh wow, you did what I wanted to do with https://github.com/AWildLeon/Glance-iCal-Events :D I recommend you test against the ICS files inside my repo. (ICS has some really weird time formats; I have files matching most of those.)

[beatrizq]

This looks so awesome! I hope the developers accept this request

[nzjrs]

This is great. Holding out hope it gets merged

[develoopeer]

Hello @Janbong. Your javascript only implementation looks quite well. I feel like most of the features mentioned in https://github.com/glanceapp/glance/pull/174#issuecomment-2676231814 implemented in your PR. Hope it will be merged