Removed old csslint package and added grunt-stylelint and stylelint
config for Wikimedia. Fixed the violations caused by this change.
Bug: T206506
Change-Id: Ieb1f087de859f5321c4f1fe65c0e3bf7b655ca15
* Instead of repeating CSS already in Minerva instead use an element
"banner-container" already in use by CentralNotice (given this is also a banner)
This removes the need for positioning styles at Minerva is delegated to handle that.
* Rewrite existing rules using mediawiki ui variables to make clearer line-height
relates to iconography
Bug: T140807
Change-Id: I1bd3fb164bbb7866e5d32367c66afae5c1933bcb