fix: allow asset(...) to be used with imported assets

[Rich-Harris]

The asset(...) function currently only allows (at a type level, at least) files inside static. Instead, it should allow any string beginning with /, so that it can be used with assets generated from imports:

<script>
  import { asset } from '$app/paths';
  import logo from './logo.png';
</script>

<img alt="logo" src={asset(logo)} />

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🦋 Changeset detected

Latest commit: 5a7c551

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Name	Type
@sveltejs/kit	Patch

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Preview: https://svelte-dev-git-preview-kit-14270-svelte.vercel.app/