Use Headless Chrome over PhantomJS for (QUnit) tests

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Goals:

• Replace PhantomJS with Puppeteer
• Remove every ugly non-obvious hack we introduced to run js:qunit

TODO:

• [x] Add useful formatted reporter
• [x] Run tests in different viewports
• [x] Resolve test file globs
• [x] Test all HTML files
• [x] Rename to js:test since it will also check for console.error unrelated to specific QUnit tests
• [x] Fix failing Slideshow test

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Basic reporter added:

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Added to new implementation