Keyboard navigation on calendar view does not prevent page scrolling

[userquin]

hi @motss, great work, I haven't use it since version 1:

Another change you will need to apply to app-datepicker is to prevent page scrolling on keyup events (only on calendar view): for example, go to your Configurable demo powered by Firebase and increase the screen font size until vertical scroll appears (Crtl ++), then focus a date on the calendar (not in dialog) and just press Arrow Up and Arrow Down moving between months => the page will scroll vertically.

This is because your handler is passive, so you cannot prevent it's propagation (I also tested to focus the target cell with preventScroll: false without success), so I suggest you to change it to not using passive event handler, use keydown instead keyup and prevent it's propagation.

If the dialog is shown on a popop instead on a dialog, it is very fustrating using the keyboard, the page will scroll up and down => just see the new Web Core Vitals concepts from Google (you can see that on chrome devtools on perfomance tab it will appear a new entry called Experience (between Frames and Main), you will see there:

Warning: Cumulative Layout Shifts can result in poor user experiences.

Originally posted by @userquin in #180 (comment)