Vector will be broken into 2 separate skins with 2 keys that represent the legacy (`vector` key) and the modern version (`vector-2022` key). The two skins (legacy aka Vector and modern aka Vector 2022) will be marked in such a way that they are hidden on Special:Preferences.
With 2 skins and a migration plan, we can manage the change iteratively, e.g. QA the 2 skins and change the defaults on different wikis as we wean ourselves off the old skin.
# Acceptance criteria
[] Vector will be broken into [[ https://gerrit.wikimedia.org/r/c/mediawiki/core/+/721106 | two internal skins ]] that are hidden in user preferences. These will have skin keys `vector` and `vector-2022`
[] Vector will be the default skin. The Vector constructor, will make use of SkinFactory::getSkinOptions to work out which skins to apply
[] The skin key for Vector will be "vector"
[] No change to end user experience.
# QA steps
- Visit preferences. I should only see one Vector skin listed.
- When I visit wiki/Special:Preferences?useskin=vector-2022 I see an additional Vector skin in preferences
- When I visit wiki/Special:Preferences?useskin=vector I see only one Vector skin in preferences