feat: offer a week-view

[gunnartorfis]

Similar to Wix's Agenda component and my current calendar component, there's a possibility to show a week view strip that is expandable to a month view.

Here's a demo of how it works in my app at the moment: https://github.com/MarceloPrado/flash-calendar/assets/5333875/90bf0dd1-db03-4483-b735-3a231fad1b42

The way I implemented it is that we render both the month view and the week view, then animate the height & opacity for each, depending on which view is visible. That is a very simple approach but I'm not sure how Wix's implementation is with the Agenda component - that seems more advanced, like they're reusing the week/rows when toggling between the week & month view.

Anyways, I'd be happy to contribute and help with such an implementation. I just wanted to open this issue so we can discuss if this is something this library would want to add support for, and if so, go into implementation planning together.