feat: support external CardView submission

[PrinceD96]

Summary

• add card.showSubmitButton for iOS and Android while preserving the existing default
• expose CardViewHandle.submit(): void for merchant-owned CTAs, matching Adyen Web's imperative submit pattern
• keep embedded cards mounted and retryable after hide(false)
• dispatch Android submit and retry operations to the main thread
• document the public API and external-submit flow

Testing

• yarn typecheck
• yarn test --runInBand (27 suites, 272 tests)
• Android testDebugUnitTest (96 tests)
• Android ktlint
• API Extractor validation
• Swift syntax parsing for the changed iOS source and test files
• changed TypeScript files pass ESLint; the full lint command is blocked by two existing Prettier errors in untouched ApplePayConfiguration.ts (and locally generated Android test reports match its broad glob)

No simulator or emulator was used.

Closes #1200

[gemini-code-assist]

Code Review

This pull request introduces support for external submission of the CardView component in the Adyen React Native SDK. It adds a showSubmitButton configuration option to hide the native submit button, exposes a submit() method via a CardViewHandle ref, and implements the native bridging logic on both Android and iOS. The review feedback highlights two critical issues: a thread-safety concern in Android's CardComponentManager where UI-bound components are interacted with on a background thread instead of the Main thread, and a potential infinite render loop in React Native's CardView due to onReadyChange being used as a dependency in useEffect.