App core: Basic analytics

[vvandijck]

<!-- Global site tag (gtag.js) - Google Analytics -->
<script async src="https://www.googletagmanager.com/gtag/js?id=G-4D98Z4471P"></script>
<script>
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  gtag('js', new Date());

  gtag('config', 'G-4D98Z4471P');
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De GA code is G-4D98Z4471P.