Support Svelte 5 in `valid-prop-names-in-kit-pages`

[lishaduck]

Description

Layouts in Svelte 5 use a children prop, which valid-prop-names-in-kit-pages (newly added to the recommended set in 3.0.0-next.16) flags

(No, this isn't really a feature request, but it's not quite a bug either.)

[baseballyama]

I think I already supported Svelte5. Could you provide REPL?
-> I got it.