Authenticate client tracker with server

[martinteoharov]

We need a way to authenticate the client tracker script with the backend. I have no idea how to approach this, but for the time being we can just stick a ClientID in the URL that imports the tracker which we can append to any further requests.

In the future we will need a better way to authenticate users which will interface with the dashboard.

[lbfalvy]

• requires user consent in the EU
• there's no point falsifying it so it doesn't have to be secure
• processing a tracked event start to finish on the server should not be too complicated.

I think just an optional key provided by the page is fine, however, I don't think it's a good idea to assume how the tracker is loaded and it should definitely be possible to change this without a page reload when the user consents to identification.

The URL is a convenient place to pass this if the page uses SSR or loads the tracker from JS, but another option would be useful, such as a key on the global this object.