fix: fall back to importing dynamic dependencies relative to SvelteKit package

[dummdidumm]

Simplifies code a bit around usage locations in our own code, and solves some issues people may have with their setups closes #11578

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🦋 Changeset detected

Latest commit: 84a45e7

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

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@sveltejs/kit	Patch

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[sunrabbit123]

That's a good PR.
I'm a user who wants this PR to work and yarn pnp to work.

However, I'm just sad that there hasn't been an update on this recently.

[Rich-Harris]

preview: https://svelte-dev-git-preview-kit-12532-svelte.vercel.app/

this is an automated message