feat(capture-rs): implement replay capture in capture-rs

[frankh]

Problem

capture is fragmented

django capture for recordings is flaky

lets move everything to rust

Changes

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Does this work well for both Cloud and self-hosted?

How did you test this code?

added unit tests

[posthog-bot]

Hey @frankh! 👋
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[oliverb123]

This is a much smaller change than I expected tbh, all looks good to me aside from 1 question about where a metric is reported

[oliverb123]

Only one note, a bit of a security/stability issue. As a general rule, you should never unwrap() in any "real" code path, only tests, without being absolutely certain the thing being unwrapped will be what you expect (and usually the thing that makes you certain of that also lets you avoid unwrap())