fix: exclude service worker directory from tsconfig

[gurpreetatwal]

The docs state that the service worker can be located at src/service-worker.js or as an index.js file within the src/service-worker directory.

Without this fix users who place the file within the directory run into Typescript errors like #11721

Follow up to #11727

Question for maintainers: Should all js/ts files in the service-worker directory be excluded or only index.js|ts|d.ts?

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Latest commit: 144ff7157bad8efb8e1ed185a1ac0d40570ab981

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@sveltejs/kit	Patch

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[gurpreetatwal]

@dummdidumm, @trueadm , @eltigerchino sorry for the ping but would one of you be able to take a look at this PR?

[teemingc]

Thank you!