fix: ensure base from $service-worker is available during dev

[teemingc]

Noticed some service worker tests weren't being run on accident. This PR re-enables them and fixes one of them by ensuring base is exported for the dev-time $service-worker module.

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Latest commit: 14fc0aa

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

This PR includes changesets to release 1 package

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@sveltejs/kit	Patch

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[teemingc]

This is taken from the prod version of base

kit/packages/kit/src/exports/vite/build/build_service_worker.js

Lines 41 to 42 in 14fc0aa

	const base = "location.pathname.split('/').slice(0, -1).join('/')";