Support the Google Analytics 4 Measurement ID

[DrDave]

Allow for the use of the new ‘Measurement ID’ that’s been introduced with the latest edition of Goole Analytics (GA4).

Refer https://support.google.com/analytics/answer/7372977?hl=en#:~:text=A%20Measurement%20ID%20uses%20the,your%20Google%20Analytics%204%20property.

Measurement ID uses the format G-XXXXXXX whereas GA3 was UA-000000-1

The snippet that surrounds the Measurement ID (when integrated) might need to be updated, too. Please investigate and confirm whether we use gtag.js already or not.