Feature: Add nested child layout, extract skeleton layout into components to reuse.

[hoangvu12]

Hello there! 👋
This PR adds #49.

Warning
Child layout only supports View component only.

What does it means?
Now you can do:

import React from "react";
import { StyleSheet, View } from "react-native";
import SkeletonContent from "./lib/SkeletonContent";

const AvatarLayout = ({ size = 100 }: { size: number }) => (
  <SkeletonContent isLoading={true}>
    <View style={{ width: size, height: size, borderRadius: size / 2 }} />
  </SkeletonContent>
);

export default function App() {
  return (
    <View style={styles.container}>
      <SkeletonContent isLoading={true}>
        <View
          style={{
            flex: 1,
            flexDirection: "row",
            marginBottom: 10,
          }}
        >
          <AvatarLayout size={50} />
          <View style={{ alignSelf: "flex-start", padding: 10 }}>
            <View style={{ width: 100, height: 10 }} />
            <View style={{ width: 70, height: 20 }} />
            <View />
          </View>
        </View>
        <View style={{ width: 300, height: 250 }} />
      </SkeletonContent>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: "black",
    padding: 10,
  },
});

This will return