feat(perf): Capture time spent redirecting before loading the current page

[dashed]

Ref:

• https://www.w3.org/TR/navigation-timing/#dom-performancetiming-redirectstart
• https://developer.mozilla.org/en-US/docs/Web/API/PerformanceTiming/redirectStart
• https://developer.mozilla.org/en-US/docs/Web/API/PerformanceTiming/redirectEnd

If there is no redirect, or if one of the redirect is not of the same origin, then values for either redirectStart or redirectEnd is 0, and thus, no span is created.

This can reveal any server or CDN configuration issues that can add any unnecessary time to the page load time.

[github-actions]

size-limit report

Path	Size
@sentry/browser - CDN Bundle (gzipped)	19.59 KB (-0.01% 🔽)
@sentry/browser - Webpack	20.42 KB (0%)
@sentry/react - Webpack	20.42 KB (0%)
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	26.55 KB (+0.04% 🔺)

[kamilogorek]

I allowed to merged it myself, as it's a simple one-liner, and I'll include in the next beta release Today :)