Consider excluding ::view-transition- from CSS scoping logic

[benmccann]

Describe the problem

From sveltejs/kit#9605:

Note that we need to add the :root selector before the pseudo-element, otherwise Svelte will scope it to the component.

I'm not that familiar with these APIs or whether this is a good idea, but wanted to note it here so that we don't lose track of it

Describe the proposed solution

Also from sveltejs/kit#9605:

We may want to omit ::view-transition-{old,new,group} from the CSS scoping logic in Svelte 4, so that idiomatic uses of the view transitions API are covered.

Alternatives considered

Status quo of adding the :root selector before the pseudo-element

Importance

nice to have