build(examples): use Vite in CSS example

[sarahdayan]

This uses Vite instead of Parcel in the CSS example.

We couldn't set up Parcel to properly compile nested CSS at all, so went with Vite which just works.

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Latest deployment of this branch, based on commit dcdfb95:

Sandbox	Source
example-instantsearch-getting-started	Configuration
example-react-instantsearch-getting-started	Configuration
example-react-instantsearch-next-app-dir-example	Configuration
example-react-instantsearch-next-routing-example	Configuration
example-vue-instantsearch-getting-started	Configuration