Log a warning when rate limit is active

[philipphofmann]

When the SDK removes an envelope item due to rate limiting, it should log a warning or error message, that surfaces even when the option debug = false. We recently had an investigation with a customer, and no events ended up in Sentry. It took us a while to determine that all envelope items were rate-limited. This was very confusing and frustrating to the customer, and they couldn't discover the problem themselves.

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1. Change rate limiting logs to level warning or error sentry-cocoa#4456
   Platform: Cocoa Waiting for: Product Owner +2
2. Android
3. Flutter
4. JavaScript
5. Log a warning when rate limit is active sentry-react-native#4193
   0 of 3
   Platform: React-Native +1