Add GA4 tracking code

[rohanpsingh]

No description provided.

[aescande]

A very good remark from @gergondet : we need to make sure that we remain GDPR-compliant.
I don't have time to look at that right now, but please check it.
A relevant page might be this.

I'd rather collect a bit less data than having to have a popup for people to select what cookies they accept.

[rohanpsingh]

Thanks, I didn't think about this, because we are not using the data with Google Singals/Ads.
There is more information here: https://taginspector.com/articles/google-analytics-4-ga4-compliant-tracking-guide/
I will read it in more details later but it looks like it'll be fine if we implement an appropriate consent pop-up.

[rohanpsingh]

@fkanehiro (@aescande )
I read a bit more about this recently. But there is no definite answer from a reliable source.
In my opinion, it should be totally OK to merge this (given our purpose is only to keep a rough track of number of site visitors).

[aescande]

You should at the very least have something for people to consent. Maybe @gergondet can will some insights.