Public API for manual replay control

[romtsn]

Similarly to web replays, we should provide public API for controlling replay behavior manually:

• start/startBuffering should start recording a replay regardless of sample rates set, with the corresponding mode
• stop should stop the replay and send it to sentry
• flush should flush all pending segments/frames to sentry

### `start/stop` current Replay
- [x] Apple impl: https://github.com/getsentry/sentry-cocoa/pull/4414
- [ ] Apple docs: (TODO)
- [ ] Android (TODO)
- [ ] https://github.com/getsentry/sentry-react-native/issues/4441
- [ ] https://github.com/getsentry/sentry-dart/issues/2558

There's also interest in permanently deactivating SR after SDK init, e.g. as described here: - getsentry/sentry-cocoa#4833

[cmanallen]

@romtsn Is this done?

[romtsn]

@cmanallen only on iOS I think, no other platform

[billyvg]

We should probably add these to the other platforms before GA so that our APIs are consistent.

[philipphofmann]

If possible, aligning the API for starting/stopping and pausing/resuming SR with continuous profiling could make sense. In other words, those keywords for SR and profiling should do similar things because otherwise, it could confuse users.

[rf-westhuizen]

Is it possible to conditionally include replay data in events sent to Sentry using the options.beforeSend callback? Specifically, I'd like to include replay data only for error-level events, while removing it from info, debug, and other non-error event types. What would be the proper approach?

[romtsn]

@rf-westhuizen what SDK? It's a little bit tricky to do that given there's currently no direct connection between error events and replay events (they are send separately in different envelopes, and only being connected through a special envelope header). Do you use sessionSampleRate or onErrorSampleRate?