fix(coverage): v8 to support source maps with multiple sources

[AriPerkkio]

Description

While setting up Vitest monorepo's coverage, noticed that V8 shows only the first file of bundled sources.

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[AriPerkkio]

Looks like bug in Vite's SSR transform:

import { fileURLToPath } from "node:url";
import { createServer } from "vite";

const server = await createServer({
  configFile: false,
  root: fileURLToPath(new URL(".", import.meta.url)),
  server: { port: 1337 },
});

await server.listen();

const ssr = await server.transformRequest("./dist/bundle.js", { ssr: true });
const web = await server.transformRequest("./dist/bundle.js", { ssr: false });

console.log({ ssr: ssr.map.sources, web: web.map.sources });
// {
//   ssr: [ '../src/first.ts' ],
//   web: [ '../src/first.ts', '../src/second.ts' ]
// }

server.close();

[AriPerkkio]

V8 coverage works fine with vitejs/vite#17677 applied locally. Generated the snapshots with that patch.

[AriPerkkio]

Needed for vitejs/vite#17677

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[AriPerkkio]

Verified that all our old tests pass with these changes when used with older Vite versions. ✅

[AriPerkkio]

/ecosystem-ci run

[vitest-ecosystem-ci]

📝 Ran ecosystem CI: Open

suite	result
aria-live-capture	✅ success
nuxt	❌ failure
nuxt-test-utils	❌ failure
elk	✅ success
effect	✅ success
zustand	✅ success
vue	✅ success
vite	✅ success
vitest-vscode	❌ failure
vitest-sonar-reporter	✅ success
vitest-github-actions-reporter	✅ success
vitest-browser-simple	✅ success
vitest-browser-examples	✅ success
vitest-coverage-large	✅ success
vitest-reporters-large	✅ success

[AriPerkkio]

I'm not sure if this is even needed. If it's removed, all tests pass just fine. Maybe let's try removing this in future and leave it here for now.