feat: simple testing library

[AdrianGonz97]

Alternative to #32

This takes more of a lightweight approach where we provide a bare minimum api for testing rather than controlling the whole testing pipeline. This should allow for better flexibility as we're no longer tied to any particular testing framework.

Notes:

• Had to rename the directory of the vitest addon as it was somehow interfering with vitest or tinypool during runtime, causing shit to randomly break
• Storybook has been pinned to v8.3.x as v8.4.x flat out doesn't work. I haven't had a moment to fully investigate the issue yet.

TODO:

• Snapshots?
• look into using vitest workspaces
• Should we continue to use degit to clone the vite templates? If so, should we pin it to a specific commit hash (see here)? Or should this be something we manage fully (perhaps as part of create)?

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pnpm add https://pkg.pr.new/sveltejs/cli/sv@275

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commit: b6d91be