build: v5 updates and refactors (#2428)

* Update JS build

- Change rollup build from API to config file
- Change output dir from lib to dist
- Update lib to dist path in related files
- Update dependencies
- Add banner comment to bundles
- Add unminified plugin bundles

* Update docs with v5 version lock and dist path

* Update docs to reference minified themes

* Clean up docs

* Update CSS build

- Change CSS build from API to CLI
- Change output dir from lib to dist
- Update lib to dist path in related files
- Update dependencies
- Add sourcemaps

* Update dependencies

* Clean up package.json and add keywords

* Fix rimraf globs on Windows

* Fix PostCSS CLI glob on Windows

* Update test-related dependencies

* Update emoji

* Add engines prop to package.json