Make `shouldResetScrollPosition` work for non-link requests

[daun]

• Currently, shouldResetScrollPosition passes in a link element
• We should make sure this still works for form requests or API requests
• The API of ignoreVisit probably makes sense to emulate here

options = {
  shouldResetScrollPosition: (url: string, { el, event }: { el?: Element; event?: Event }) => boolean
}

How important is this feature to you?

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

[daun]

Just realized this is completely obsolete in swup 4 — we can just set context.scroll.reset to false in the transitionStart hook.