Add modalComponent prop

[ersefuril]

In some cases, the default Modal component from react-native should be replaced by another one (typically, when using a library such as react-native-web).
The new prop modalComponent will allow you to achieve that, with minimal code changes.
Feel free to ask if I need to edit something.

[Gabrielfcs]

Excellent change, because in addition to allowing the use of other modal libs, it also allows the use of the statusBarTranslucent prop of the React Native modal component that even using the topAjustment prop of this lib, it is still not possible to cover the entire screen with the backdrop