Upgrade to Storybook 8

Chains the earlier majors: a project several majors behind needs only this recipe, and upgrades the dependencies once, straight to 8.x, so no intermediate version has to resolve. Upgrade storybook and the @storybook/* frameworks, builders and addons that publish in step with it to 8.x in package.json. Not done by this recipe: the .storybook/main and preview configuration changes as the Storybook 8 migration guide lists them, Node.js version requirements, and packages with their own version line such as @storybook/test-runner; run npx storybook@8 automigrate afterwards.