Make error pages responsive

## What does this MR do?

This MR makes error pages responsive design and all users have better experiences on 404/422/500/502/503/in-deploy error.

## Are there points in the code the reviewer needs to double check?

n/a

## Why was this MR needed?

404/422/500/502/503/in-deploy error pages were designed only for PC and not good for mobile users.

## What are the relevant issue numbers?

Closes #19345

## Screenshots (if relevant)

### PC
![improved-404-lg-v3](/uploads/280f48f95bd446888a81cc2150877cd8/improved-404-lg-v3.png)

### mobile

(with `max-width: 40vw` for `img` (@connorshea) and `max-width: 800px` for `hr` (@annabeldunstone) )
![improved-404-xs-v3](/uploads/9764aac3992dedb6b437045943a07fe5/improved-404-xs-v3.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5000