Fix Android Build Error: Kotlin Argument Type Mismatch (ReadableMap? vs ReadableMap) (#1971)

[erenkeskin]

Summary

This PR fixes a build error on Android related to Kotlin argument type mismatch in the Stripe React Native SDK.
The root issue was that Dynamic.asMap() can return null (i.e., type ReadableMap?), while the functions were expecting a non-nullable ReadableMap.
This led to compilation failures when building on Android with React Native 0.70+.

The PR updates method signatures and usages in both EmbeddedPaymentElementViewManager and AddToWalletButtonManager to safely handle nullable ReadableMap types, preventing argument type mismatch and build errors.

Motivation

The motivation is to resolve issue #1971, which is a blocking Android build error for anyone using the Stripe React Native SDK with newer versions of React Native (0.70 and above).

The error message is similar to: Argument type mismatch: actual type is ‘ReadableMap?’, but ‘ReadableMap’ was expected.

See also:

• #1971
• [Relevant lines in EmbeddedPaymentElementViewManager.kt and AddToWalletButtonManager.kt]

Testing

• [x] I tested this manually: Android build now succeeds, and EmbeddedPaymentElement/AddToWalletButton behave as expected in our production app.

Documentation

• [x] This PR does not result in any developer-facing changes.

Additional context

• See the original issue #1971 for reproduction steps and error details.
• This PR only modifies type handling and null-safety for Kotlin interop, no changes to JS API or business logic.