add childrenContainerStyle prop to be able to style the children container View

[thoounn]

To be able to place the "Click me" button where ever you want without breaking the popup position.

Ex:

<DateRangePicker
    ...
    backdropStyle={styles.datePickerBackdropStyle}
    childrenContainerStyle={styles.datePickerChildrenContainerStyle}
>
    <Text>Click Me</Text>
</ DateRangePicker>

And for the styles:

datePickerBackdropStyle: {
    width: "100%",
    height: "100%"
},
datePickerChildrenContainerStyle: {
    position: "absolute",
    top: 0,
    left: 0
}