Allow React Native Android devs to manually report exceptions to HB from native modules.

[andreybutov]

This is a follow-up to #1050 .

The problem we have is that we cannot hook into unhandled native Android exceptions from the main thread for React Native, because the RN library itself handles exceptions on the main thread, and doesn't rethrow to allow for interception.

To make things a little better for developers, we need to add a way for them to still be able to report native Android errors to Honeybadger, even if we can't catch unhandled native exceptions automatically from the main thread.

We will add notify method(s) to the native layer of HB RN (Android only) that will allow developers to report a native Android exception directly to Honeybadger. That way, if they are implementing their own native Android modules, or are explicitly calling Android native modules from their code, they can wrap those calls in try catch blocks of their own, and then send any caught native exceptions to Honeybadger directly from native Android code.