**Reason**:
The `Premoderation` extension is to be archived for a few reasons:
* it is orphan, has been imported in Gerrit in 2013 and hasn't receive any worth while code.
* the extension has multiple tests failures (T157417 T155831 + another not filled)
* It puts edits in a moderation queue by triggering an error!
* wikiapiary doesn't list any wiki having it installed
- [x] ~~Archive documentation on `mediawiki.org`~~ (no page)
- [x] Remove from `mediawiki/extensions` ( along with in `.gitmodules`)
- [x] Remove tests in `integration/config` ( `zuul/layout.yaml` )
- [x] Remove from `translatewiki` ( `groups/MediaWiki/mediawiki-extensions.txt`)
- [ ] ~~Remove manifest/other references from `mediawiki/vagrant` if they exist~~
- [ ] Empty repository and add a OBSOLETE file.
- [ ] ~~Archive Phabricator project <#ProjectX> for associated extension~~
- [ ] ~~Edit Phabricator project <#ProjectX> description for associated extension with a link to this ticketskin
- [ ] Archive the extension's diffusion repository: rEPRM
- [ ] Mark the repository read-only in Gerrit: https://gerrit.wikimedia.org/r/#/admin/projects/mediawiki/extensions/Premoderation
- [ ] Delete the GitHub mirror: https://github.com/wikimedia/mediawiki-extensions-Premoderation