build: Updating dependencies

composer:

• mediawiki/mediawiki-codesniffer: 34.0.0 → 35.0.0
• mediawiki/minus-x: 1.1.0 → 1.1.1

npm:

• eslint-config-wikimedia: 0.17.0 → 0.18.1

Additional changes:

• Remove direct "stylelint" dependency in favor of "grunt-stylelint".

Change-Id: I6afb86d1495488f2c00999151fa5a24826344516