Googlepay kotlin conversion

[chinghlinn]

Summary of changes

• Convert BraintreeGooglePayWalletConstants, GooglePayActivity, GooglePayActivityResultContract, GooglePayCapabilities, GooglePayClient, GooglePayException, GooglePayInternalClient, GooglePayLauncher, GooglePayPaymentAuthRequestParams, GooglePayPaymentAuthResult, GooglePayRequest, and ReadyForGooglePayRequest to Kotlin.
• GooglePayRequest remains Parcelable pattern to implement Parcelable interface because the HashMap properties have values of JSONObject type which does not implement Parcelable interface and cannot utilize the kotlin-parcelize plugin.
• Suppress warnings SwallowedException, LongMethod, MaximumLineLength, TooGenericExceptionCaught, CyclomaticComplexMethod, NestedBlockDepth, MaxLineLength as refactoring is required.

Checklist

• [x] Added a changelog entry
• [ ] Relevant test coverage

Authors

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