DRYed the code

Changed new rules to warnings

Manual prettified and added stylelint rules

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/58625

Added stylelint to static-analysis
Updated yarn dependencies
CSS Fixes and rule adoptions of stylelint
Added stylelint-scss
Deduplicated yarn.lock to clear dependencies

First round of advanced stylelint rules

Mainly Vendor prefix updates related to flex

Updates to more webkit specific vendor prefixes

Finished all vendor specific fixes

Moved now 4 rules to warning

Fixed the new scss lint problems

More stylelint adaptions after rebase

Added stylelint to static-analysis
Updated yarn dependencies
CSS Fixes and rule adoptions of stylelint
Added stylelint-scss
Deduplicated yarn.lock to clear dependencies