add react native event emitter methods

[calebmackdavenport]

Ever since React Native 65+, launching scandit produces quite a few warnings. Just wanted to request this change.

Examples of other packages:
software-mansion/react-native-reanimated@2.2.0...2.2.1#diff-791d943e777c3aeed7f019e3261ef3f1447da24e60c47d7cc90f5d520121a00dR241

https://github.com/segmentio/analytics-react-native/blob/master/packages/sovran/android/src/main/java/com/reactnativesovran/SovranModule.kt#L35

RN 65 changelog:
https://www.reactnative.com/react-native-v0-65-x-released

I think this is the root cause on the above page:

NativeEventEmitter no longer inherits from EventEmitter, so it no longer implements removeListener and removeSubscription. Instead, use the remove() method on the subscription object returned by addListener. (d39643b9de by @yungsters)

[kuglemic]

Thanks for the Pull Request!
Can someone please merge this? The warnings are annoying.