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:

• Added the "composer phan" command to conveniently run phan.
• Removing manual extensions for eslint.

Change-Id: If22b3f6cb0b3263183496f9cbe4227b13cb1e32d