feat(perf): Add experimental option to improve LCP collection

[k-fish]

Summary

This will add an experimental option (options._metricOptions._reportAllChanges) that will set 'getLCP' to always report. Now that we are recording LCP element, it should be sufficient to collection the additional information and let the user pick the appropriate LCP element in the ui to improve accuracy dynamically instead. We'd like to test this out on Sentry first.

We can probably cut this as a beta to try it out first.

Refs VIS-1199

[github-actions]

size-limit report

Path	Size
@sentry/browser - CDN Bundle (gzipped)	21.66 KB (0%)
@sentry/browser - Webpack	22.67 KB (0%)
@sentry/react - Webpack	22.71 KB (0%)
@sentry/browser + @sentry/tracing - CDN Bundle (gzipped)	29.11 KB (+0.06% 🔺)

[AbhiPrasad]

Shipping this under an option for now, we can remove the option at a later time.

To use this, enable the option in SDK init:

Sentry.init({
  integrations: [
    // other options
    new Integrations.BrowserTracing({
      _metricOptions: {
        _reportAllChanges: true,
      },
    });
  ],
});