Creates a new skins.vector.search module that
replaces the searchSuggest module from MediaWiki core.
This module creates a new Vue app using the WVUI
search widget for the new search experience.
The legacy search input form is still retains on pageload,
and the new search kicks on search input focus.
In order to manage that transition, the legacy search
input is styled to resemble the new WVUI input, and the
new input is manually focused after the component mounts.
Vue is also added as a dev-dependency to help with
type-checking.
Other changes:
* the entry in skin.json is reordered alphabetically after
skins.vector.js
Bug: T264355
Change-Id: Ibb9561a77a14734297cb4d0ddcd415fc0750b45d
