Fixes: https://invent.kde.org/plasma/plasma-mobile/-/issues/423
We currently listen to when the volume changes, which wouldn't happen if
the user reaches 0% or 100% and continues trying to press the volume
button. Instead, listen to OSD events for determining when to open the
popup.
We so far have been recreating the background elements for all the item throughout the shell. This merge request simplifies this by unifying these elements into a single component, making is easier to keep things at a consistent design while also being able to adjust things when needed in the future.
Per request, I tried to keep thing looking mostly the same as before.
The first picture is what the action drawer looks like now, the one after is with these changes.
This merge request adjust animations in the VolumeOSD and NotificationPopup to bring consistency and to make it feel better when swiping up a notification.
