fix: manually forward activity results to paymentLauncherFragment

[charliecruzan-stripe]

Summary

Added forwarding of activity result to the paymentLauncherFragment

Motivation

Without this, only on older versions of RN, the result is never passed to the fragment and promises would never resolve for calls to confirmSetupIntent and confirmPayment.

Testing

• I tested this manually
• I added automated tests

It should be noted that this can duplicate calls to the payment result callback, but it's not really an issue since calling promise.resolve on an already resolved promise is a no-op.

When we don't want to support RN 64 and below anymore, I believe these three lines can be removed.

Documentation

Select one:

• I have added relevant documentation for my changes.
• This PR does not result in any developer-facing changes.