Manually start and stop session recordings

[marandaneto]

Description

Ticket: https://posthoghelp.zendesk.com/agent/tickets/20809

Add APIs to allow for manual start/stop of session recordings

• iOS
• Android
• RN
• Flutter

https://github.com/PostHog/posthog-js/blob/1b57ea9f6b7736f3e3fce0fd512b467ddb35c5d9/src/posthog-core.ts#L1837

This option is an alternative for:

• Sampling
• Minimal duration
• Screen by screen basis