eslint: Enforce no-var and autofix

Change-Id: I388b79f1498c59ba060588a10e9c5dbc0da8b734

• modules/.eslintrc.json[diff]
• modules/ext.guidedTour.lib.internal.js[diff]
• modules/ext.guidedTour.lib/ext.guidedTour.lib.Step.js[diff]
• modules/ext.guidedTour.lib/ext.guidedTour.lib.StepBuilder.js[diff]
• modules/ext.guidedTour.lib/ext.guidedTour.lib.Tour.js[diff]
• modules/ext.guidedTour.lib/ext.guidedTour.lib.TourBuilder.js[diff]
• modules/ext.guidedTour.lib/ext.guidedTour.lib.main.js[diff]
• modules/mediawiki.libs.guiders/mediawiki.libs.guiders.js[diff]
• modules/tours/firstedit.js[diff]
• modules/tours/firsteditve.js[diff]
• modules/tours/onshow.js[diff]
• modules/tours/test.js[diff]
• tests/qunit/ext.guidedTour.lib.tests.js[diff]