Add a simple data layer to visits

[adriaanvanrossum]

It would be cool to have some sort of simple data layer within page views.

For example showing if visitors are logged in or not, looking add a specific product.

To keep it privacy friendly we would need to have some kind of predefined variables like product slugs. This would be a nightmare to implement for the customers, so we need a better solution that is still privacy friendly. Just thinking our loud: we could use the page title. It usually contains the relevant information. Although this is more useful for events as the product page has already a unique URL.

It'd also be great to tag visits so I can compare analytics logged in vs. not logged in.

Thanks to Daniel (https://twitter.com/mrdanielschwarz/status/1325072980230066176)

Related issue #473

[adriaanvanrossum]

Duplicate of #552