fix: resolve assets.directory path from wrangler config

[GauBen]

Hi!

This PR fixes a bug in the current version of the Cloudflare adapter: it always assumes that the wrangler.json config file is in the same directory as the .svelte-kit directory.

With this fix, the wrangler.json can be placed anywhere (parent and children directories work)

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[changeset-bot]

🦋 Changeset detected

Latest commit: 5a02a40

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

This PR includes changesets to release 1 package

Name	Type
@sveltejs/adapter-cloudflare	Patch

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-14036-svelte.vercel.app/

[eltigerchino]

Thank you!