fix(browser): Ensure pageload & navigation spans have correct data

[mydea]

This PR fixes two things about our idle spans emitted from browserTracingIntegration:

1. The navigation name was sometimes incorrect. This is because we look at window.location.pathname at the time when the popstate event is emitted - but at this point, this may not be updated yet. So a navigation transaction would possibly have the pathname of the previous page as transaction name.
2. The request data is also possibly incorrect - this is set by HttpContext integration at event processing time. However, at this time the window.location data is also usually already of the following navigation, so the pageload would often have wrong request data associated to it. Now, we store this on the current scope at span creation time to ensure it is actually correct.

WIP on top of #16277 for tests

[github-actions]

size-limit report 📦

Path	Size	% Change	Change
@sentry/browser	23.97 kB	added	added
@sentry/browser - with treeshaking flags	23.63 kB	added	added
@sentry/browser (incl. Tracing)	38.27 kB	added	added
@sentry/browser (incl. Tracing, Replay)	76.38 kB	added	added
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	69.41 kB	added	added
@sentry/browser (incl. Tracing, Replay with Canvas)	81.14 kB	added	added
@sentry/browser (incl. Tracing, Replay, Feedback)	93.23 kB	added	added
@sentry/browser (incl. Feedback)	40.77 kB	added	added
@sentry/browser (incl. sendFeedback)	28.71 kB	added	added
@sentry/browser (incl. FeedbackAsync)	33.6 kB	added	added
@sentry/react	25.79 kB	added	added
@sentry/react (incl. Tracing)	40.28 kB	added	added
@sentry/vue	28.36 kB	added	added
@sentry/vue (incl. Tracing)	40.08 kB	added	added
@sentry/svelte	24 kB	added	added
CDN Bundle	25.19 kB	added	added
CDN Bundle (incl. Tracing)	38.27 kB	added	added
CDN Bundle (incl. Tracing, Replay)	74.18 kB	added	added
CDN Bundle (incl. Tracing, Replay, Feedback)	79.59 kB	added	added
CDN Bundle - uncompressed	73.5 kB	added	added
CDN Bundle (incl. Tracing) - uncompressed	113.36 kB	added	added
CDN Bundle (incl. Tracing, Replay) - uncompressed	227.31 kB	added	added
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	240.14 kB	added	added
@sentry/nextjs (client)	41.92 kB	added	added
@sentry/sveltekit (client)	38.74 kB	added	added
@sentry/node	159.15 kB	added	added
@sentry/node - without tracing	97.9 kB	added	added
@sentry/aws-serverless	124.41 kB	added	added