Add react ref and key props to components

[Freddy03h]

• Add ref prop to NavigationContainer (important for universal link scenario)
• Add key prop to components

[MoOx]

That's weird. We should not have to define key, they should be automatic with the jsx ppx...
But I made a test & the compiler is yelling indeed.
We should only add the ref when we create the makeProps by hand and not when we have [@react.component] (= ppx, so auto ref)

[MoOx]

This one seems unecessary

[Freddy03h]

It doesn't work without it, and I looked on other project to do it : https://github.com/reason-react-native/datetimepicker/blob/f479766c79ce24248c8752c2b1a6e5edb35bb2b1/src/ReactNativeDateTimePicker.re#L21

[Freddy03h]

The doc say the ppx add the key but not the ref : https://reasonml.github.io/reason-react/docs/en/components#reactcomponent

[Freddy03h]

I added key only for components made with makeProps

[MoOx]

Oh that's right, I read too quickly!

[MoOx]

5.0.1 is out :)