feat(adapter-cloudflare): expose the external ESBuild option

[allezxandre]

This PR exposes the external ESBuild option from the adapter-cloudflare package.

Had a 3rd party package importing some node-native modules without the node: prefix, making the build fail.

Providing externals to the adapter's build step like the following allowed me to build:

esbuildOptions: {
    external: ["fs", "crypto", "url", "os", "path", "stream", "zlib", "net", "tls", "http", "https"]
}

Might help the following issues:

• Modules not resolved with adapter-cloudflare (buffer, stream, util, crypto) #3564
• Support Node Compat in Cloudflare Adaptor #10028

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Latest commit: 16b7391

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

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Name	Type
@sveltejs/adapter-cloudflare	Minor

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[allezxandre]

In the following issue:

• Support Stripe in @sveltejs/adapter-cloudflare integrations #6547

the external build option might have helped as a temporary workaround while waiting for Stripe to fix their package imports

[benmccann]

please see my comment here: #10424 (comment)

[benmccann]

I'm going to close this in favor of #10424, which seems closer to being ready to merge