refactor: added warning if async storage is not found

[joker23]

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Related issues

sdk-1676

Describe the solution you've provided

• Added a warning message for when async storage is not found and is being mocked.
• Added tests to verify behavior with custom and default storage implementations.
  Provide a clear and concise description of what you expect to happen.

---

Note

Introduces a logger-aware AsyncStorage initialization with a fallback and verifies storage selection behavior.

• Refactors ConditionalAsyncStorage into getAsyncStorage(logger) that logs a warning and returns a mock when @react-native-async-storage/async-storage is unavailable
• Updates PlatformStorage to initialize via getAsyncStorage and proxy get/set/clear to the resolved instance
• Adds ReactNativeLDClient.storage.test.ts to assert use of custom storage, absence of warnings, and default PlatformStorage instantiation and method calls when no custom storage is provided
• Minor comment/whitespace cleanup in EventSource.ts

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