A11y: allow disabling animated scroll from visit object

[Philipp Daun]

Describe the feature

• Add a visit.scroll.animate key that gets set right on visit:start by this plugin
• Allow other plugins (mainly a11y-plugin) to unset the flag and disable animations

Alternatives considered

• Use the existing suggested solution with matchMedia
• As a user, I'd prefer having an option on the a11y-plugin to group such behavior in one place

How important is this feature to you?

• Nice to have
• Would make my life a lot easier
• I cannot use swup without it

[Rasso Hilber]

Nice! Great idea. The visit object is unlocking a lot of previously hard-to-slove features 🗝️