Add scrollend to <svelte:window> event type

[janosh]

Describe the problem

scrollend has reached 71% browser support.

Describe the proposed solution

While this works as expected:

<svelte:window on:scrollend={() => console.log(`scrolling has finished`)} />

I'm getting a type error

Object literal may only specify known properties, and '"on:scrollend"' does not exist in type 'HTMLProps<"svelte:window", HTMLAttributes>'.ts(2353)

Importance

nice to have