Upgrade to Storybook 7

Upgrade storybook and the @storybook/* frameworks, builders and addons that publish in step with it to 7.x in package.json. Also runs MigrateStorybook7: replaces start-storybook and build-storybook with storybook dev and storybook build, moves a renderer plus @storybook/builder-webpack5 or @storybook/builder-vite to the @storybook/<renderer>-webpack5 or -vite framework (in package.json and in framework and core.builder of .storybook/main), removes @storybook/manager-webpack5 and adds the storybook package. Not done by this recipe: the other .storybook/main and preview configuration changes as the Storybook 7 migration guide lists them, the Babel configuration that a webpack5 framework needs to compile TypeScript stories (the missing-babelrc item of automigrate), Node.js version requirements, and packages with their own version line such as @storybook/test-runner; run npx storybook@7 automigrate afterwards.