Checkbox.Item: Make the underlying TouchableRipple more configurable

[haykerman]

Is your feature request related to a problem? Please describe.
I've applied border radius to Checkbox.Item, and it seems to work as expected. However, when the item is pressedIn, the underlying touchable ripple doesn't respect the item's border radius.

Describe the solution you'd like
Expose an API to tweak the TouchableRipple through rippleStyle or containerStyle.

Describe alternatives you've considered
I've considered not using the Checkbox.Item and manually implementing the component with desired level of configuration. But it's a much bigger lift.

Additional context