feat: add hideCardNicknameField configuration option

[sakksham7]

Summary

• Adds hideCardNicknameField boolean configuration option to PaymentSheet.Configuration
• When set to true, the card nickname input field will be hidden during card payment flow
• Default value is false (nickname field is shown)

Changes

• Added hideCardNicknameField property to Configuration data class
• Added bundle serialization for passing to React Native layer
• Added builder method hideCardNicknameField(Boolean) for Java/Kotlin configuration

Usage

val configuration = PaymentSheet.Configuration.Builder("Merchant Name")
    .displaySavedPaymentMethodsCheckbox(true)
    .hideCardNicknameField(true) // Hides the nickname field
    .build()