fix: use snippet as parent element of snippets childrens in validator

[paoloricciuti]

Svelte 5 rewrite

Fixes #11462 by setting snippet as the parent_element in the validator statement when a Snippet is encountered. This obviously could allow for something like this

<table>
    <tbody>
        <tr>
            {#snippet cell(v)}Value: {v}{/snippet}
            {@render cell(1)}
        </tr>
    </tbody>
</table>

that will produce invalid html but that is already true if you declare the snippet outside of table.

{#snippet cell(v)}Value: {v}{/snippet}
<table>
    <tbody>
        <tr>
            {@render cell(1)}
        </tr>
    </tbody>
</table>

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[changeset-bot]

🦋 Changeset detected

Latest commit: 1aabba7

The changes in this PR will be included in the next version bump.

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[Rich-Harris]

thanks 👍