Fixes one of the items that was mentioned in #25854.
It fixes the warning in `with-next-page-transitions` by moving the viewport tag to `_app.js` from `_document.js`
**Affected examples**
with-segment-analytics
with-slate
with-portals-ssr ( _with-portals-ssr is based on a package not being updated in the last year_)
with-videojs
with-next-page-transitions
with-firebase-cloud-messaging
with-dynamic-app-layout
with-dynamic-import
with-next-transition
with-carbon-components
with-cerebral
with-custom-babel-config
Here and there I have removed some redundant imports as well. I believe with this PR, there are only 1 or 2 examples left using class-based components. If by any chance you find any, let me know and I'll refactor them too.
If you don't like anything or you want me to change something, please let me know.
**If there is anything else you'd like me to help with, I would be honored to assist.**
Per https://github.com/zeit/next.js/issues/12964
* with-ant-design
* with-dynamic-import
* with-iron-session
* with-monaco-editor
* with-next-page-transitions
* with-react-with-styles
* with-style-sheet
* with-why-did-you-render
Tested each example, working as intended, no additional issues presented
* Remove micro example
* Remove page that uses getInitialProps
* Update with-docker example
* Update dynamic import example
* Update Fela example
* Update Flow example
* Update framer motion example
* Remove freactal example
* Remove with-higher-order-component
* Remove with-immutable-redux-wrapper as it shows avenues to performance issues
* Remove example that doesn't have usage
* Update with-kea
* Remove example that is not used
* Update next-page-transitions example
* Remove next-routes example as dynamic routes are supported by default
* Add link to documentation
* Update Overmind example
* Update pretty-url-routing example
* Remove update with low usage
* Update with-react-ga example
* Update React Helmet example
* Remove mobile-detect from carousel example
* Remove react-useragent as it shows a bad practice
* Remove react-uwp example as it has low usage
* Remove recompose example as it shows outdated practices
* Remove refnux example as it has low usage
* Remove example that can be created using api routes
* Update with-segment-analytics
* Update socket.io example
* Remove socket.io example as it's shows bad practices
* Update static export example
* Update universal configuration example
