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.

Tasks

Beta Give feedback

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