[Feature Request]: propagate backend generated trace id to frontend

[maciekm]

propagate backend generated trace id to frontend

If the frontend is served by a backend server we cannot connect those traces. There should be a way to pass the trace id from the backend to the frontend.

example:

Because JavaScript code running in a browser cannot read the response headers of the current page, the trace data must be transmitted in the response itself, specifically in tags in the of the HTML sent from your backend.

https://docs.sentry.io/platforms/javascript/guides/react/performance/connect-services/#pageload