Update Shopify Script for Facebook Limited Data Use from Data Sharing

[mfbrown]

As a web developer, I want to use the status of the data sharing flag in the eth_cmp cookie to block Facebook within Shopify.

AC

Update the Shopify documentation to reflect the changes required to support blocking the data sharing use case.

The emp-shopify.js snippet is updated to incorporate group5 from the eth_cmp cookie, so that it can be exposed to the Shopify tracker.