Allow configuring a custom event store in React Native tracker

[matus-tomlein]

After having reasoned a bit on it, I have an absurd idea. What if the React Native tracker accepts a storage interface in newTracker? This would allow consumers to define other storage instead of defaulting to AsyncStorage. For example, MMKV is a popular alternative in the React Native community that could be used alternatively.

Originally posted by Valerio Belli (@valeriobelli) in #1409