Investigate PrimitiveConverters.test.ts failures

[eringram]

Look into cesium-renderer's PrimitiveConverters.test.ts failures showing this error:

Vitest caught 1 unhandled error during the test run.
This might cause false positive tests. Resolve unhandled errors to make sure your tests are not affected.

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ Unhandled Rejection ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯
Error: [MSW] Failed to register a Service Worker for scope ('http://localhost:63315/') with script ('http://localhost:63315/mockServiceWorker.js'): Service Worker script does not exist at the given path.

Did you forget to run "npx msw init <PUBLIC_DIR>"?

Learn more about creating the Service Worker script: https://mswjs.io/docs/cli/init
 ❯ getWorkerInstance ../../common/temp/node_modules/.pnpm/[email protected]_@[email protected][email protected]/node_modules/msw/lib/browser/index.mjs:255:13
 ❯ startWorkerInstance ../../common/temp/node_modules/.pnpm/[email protected]_@[email protected][email protected]/node_modules/msw/lib/browser/index.mjs:1265:24
 ❯ SetupWorkerApi.start ../../common/temp/node_modules/.pnpm/[email protected]_@[email protected][email protected]/node_modules/msw/lib/browser/index.mjs:3077:26

Possible solutions

1. Figure out why MSW is required. If including it is reasonable, include pretest and posttest package.json scripts to add mockServiceWorker.js and clean up after
2. Switch to using sinon to mock in PrimitiveConverters.test.ts instead of vi.mock() (I suspect that might be related bc itwinjs doesnt use vi.mock() anywhere else)