Allow Google Tracking ID to be set

[ADefWebserver]

https://support.google.com/analytics/answer/1008080?hl=en

Find your Tracking ID and global site tag Sign in to your Analytics account. Click Admin. Select an account from the menu in the ACCOUNT column. Select a property from the menu in the PROPERTY column. Under PROPERTY, click Tracking Info > Tracking Code.

Your Tracking ID is displayed at the top of the page.

Your global site tag is displayed farther down the page in a text box under Website Tracking > Global Site Tag (gtag.js)

[ADefWebserver]

See: https://developers.google.com/analytics/devguides/collection/analyticsjs/

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ga('create', 'UA-XXXXX-Y', 'auto');
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<script async src='https://www.google-analytics.com/analytics.js'></script>
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