fix: add elevation to wrapper style

[pan-pawel]

Resolve #1225

Motivation

Without property elevation in wrapper style there is no shadow on android.

With elevation added to wrapper style

<Wrapper
        style={
          [
            { backgroundColor, zIndex, elevation },
            shadow(elevation),
          ] as StyleProp<ViewStyle>
        }
      >

Additional
since we have default elevation value

const {
  [..]
  elevation = 4,
  [..]
} = StyleSheet.flatten(style) || {};

we don't need to check if it's present

elevation &&  shadow(elevation),

so

shadow(elevation),

isn't enough?

[callstack-bot]

Hey @pan-pawel, thank you for your pull request 🤗. The documentation from this branch can be viewed here.

[franziz]

Great!