Don't try to @render svelte components in FlexRender

[dberlin]

Svelte Components should not be @render'd, only snippets get @render'd, per the docs.

Unlike Svelte 4, the Component in FlexRender will already be dynamically evaluated.

This fixes examples/svelte/sorting for Svelte 5.

The failure around undefined headers there was because trying to @render a component like this code did does not do anything sane to it.