Add support for Google Analytics 4

[jonespm]

We should add basic Google Analytics support to this application.

This will probably be via the a React library like this one. https://github.com/PriceRunner/react-ga4
This will need to be configured.

Also the CSP will need to be modified after #220 to include www.google-analytics.com (or whatever appropriate address) to both CSP_SCRIPT_SRC and SCP_IMG_SRC.