Add resource request timing data to resource spans #17554
Description
Description
The PreformanceResourceTiming entries emitted by the browser's performance API include a lot of request timing data that we currently don't pick up. We should add these data points as span attributes to the resource spans so that our product can show this information.
Most importantly, we should include responseStart which is the equivalent to TTFB for resource spans (and the product can then call it TTFB or augment the value in whatever way we see fit).
Related: #10995 (we should just do this as well)