Report dropped spans in client reports

[lucas-zimerman]

Description

Meta issue: https://github.com/getsentry/projects/issues/70

### Blocked by
- [ ] https://github.com/getsentry/sentry-java/issues/3527
- [ ] https://github.com/getsentry/sentry-cocoa/issues/4156
- [ ] https://github.com/getsentry/sentry-javascript/issues/12727

[github-actions]

This issue has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you label it Status: Backlog or Status: In Progress, I will leave it alone ... forever!

---

"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀

[krystofwoldrich]

Requires JS https://github.com/getsentry/sentry-javascript/releases/tag/8.15.0 or newer (getsentry/sentry-javascript#12751)

Or JS https://github.com/getsentry/sentry-javascript/releases/tag/7.119.0

Currently 1.0.0-beta.1 has 8.9.2

[kahest]

1.0.0 uses JS 8.27.0 so we should be good