Add StackView with customizeable animations
This component makes it easier to tweak the animations of a StackView for different situations, including the ability to switch between vertical and horizontal movement animations.
This is a more refined and reusable version of the custom StackViews I made for kickoff and plasma-pa. @ngraham requested that I make this and I've finally gotten around to it.
The animations happen to be pretty much the same as the ones used by PageRow.
I'm not so sure about the component name since it's a bit generic, but this isn't really that special of a component either. Not much API or behavior is added on top of the normal StackView behavior, just enough to make it so animation tweaks no longer require completely rewriting the transitions.
See documentation in the QML file for more details.
Even though this isn't in PlasmaExtras or PC3, this should be safe to use in Plasmoids despite being a Kirigami component. The only exception is that the duration property defaults to Kirigami.Units.longDuration instead of PlasmaCore.Units.longDuration, but it's not hard to just change the duration value and they're identical in practice anyway.