- move all source code in `src` as it's, by convention in SB monorepo, the source folder for Babel
- update `.babelrc.json` to ignore all templates files
- add `prepare` NPM script as in all other libs
- update `cleanup` stage of `prepare` script to avoid removing anything from `@storybook/cli/dist/generators/**/template*` folder because there are the template files that will be copied to initialize SB on users' projects