function resolveViteRoot(viteConfig) {
	return normalizePath(viteConfig.root ? path.resolve(viteConfig.root) : process.cwd());
}
vite passes unresolved `root`option to config hook but we need the resolved value, so do it here

@see https://github.com/sveltejs/vite-plugin-svelte/issues/113
@see https://github.com/vitejs/vite/blob/43c957de8a99bb326afd732c962f42127b0a4d1e/packages/vite/src/node/config.ts#L293

@param {import('vite').UserConfig} viteConfig
@returns {string | undefined}