feat(web-vitals): Capture extra information from LCP and CLS web vitals.

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Be able to capture extra information from LCP and CLS web vitals.

For LCP, we'd like to know the element (or image) that contributed the largest contentful paint:

• https://wicg.github.io/largest-contentful-paint/#sec-largest-contentful-paint-interface
• https://developer.mozilla.org/en-US/docs/Web/API/LargestContentfulPaint#Properties

For CLS, we'd like to know the top 5 DOM nodes contributing the the CLS scores:

• https://wicg.github.io/layout-instability/#layoutshiftattribution
• https://wicg.github.io/layout-instability/#source-attribution

These will be surfaced in the product to indicate source of poor LCP or CLS scores.

TODO

• add DOM element source for FID

[github-actions]

size-limit report

Path	Size
@sentry/browser - CDN Bundle (gzipped)	19.62 KB (-0.01% 🔽)
@sentry/browser - Webpack	20.46 KB (0%)
@sentry/react - Webpack	20.46 KB (0%)
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	26.72 KB (+0.41% 🔺)

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I'm going to hold off merging this as there might be changes I'd like to put in.

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Closing this in favour of #3427 . I will add the CLS portion in a separate PR if there is a product need for it.