fix: use wrangler CLI to bundle worker

[eltigerchino]

fixes #13300

This PR uses the Wrangler CLI to bundle the server into a single worker file. Cloudflare has no plans on publishing a public API for this and recommends using the CLI wrangler deploy --dry-run command to achieve this.

I'm not sure if this is the best way to create a build artefact since we're bundling the worker once and it gets bundled again by Wrangler during deployment (unless the user specifies --no-bundle option but this doesn't exist with Git integration). The double bundling lead to a 13kb increase in the final worker size when tested on a SvelteKit default template project. It might be better to wait for the Vite environment API integration and see if we can get the adapter to influence Vite to bundle in the node dependencies.

This PR also adds a simple test that checks if an app build is successful and works in the Wrangler dev environment.

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Latest commit: 4f757f6

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Name	Type
@sveltejs/adapter-cloudflare	Patch

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