…rer` prop (#17270)

Svelte renamed the internal renderer prop from `$$payload` to `$$renderer`
in Svelte 5.x (#14433 fixed the Svelte renderer check). The Solid renderer
copies that check to exclude Svelte components from being claimed as Solid,
but was never updated to cover the new prop name.

Projects that mix `@astrojs/solid-js` with `@astrojs/svelte` and use a
newer Svelte 5 release now compile components with `$$renderer`, which the
Solid renderer doesn't recognise, causing it to render those Svelte components
as empty strings instead of passing them to the Svelte renderer.

Fixes by mirroring the same two-prop check that the Svelte renderer already uses.