Change [cornerRadius] prop to support rounding edges on both sides

[boygirl]

From @FranciscoMurias on November 17, 2017 9:28

It would be extremely useful to change the cornerRadius prop to also support objects like these:
cornerRadius={{ top: 10, bottom: 10 }}
The corner radius only being applied on top atm, and it would give users a greater element of customizability to their graphs.

This would allow for graphs like this:

At the moment we can only do this:

This would also be extremely useful in the pieChart graph for situations like this:

Being able to define either a global corner radius for the start and end point of a graph, or give it a object setting each individual edge is a cool option to have ;)

Copied from original issue: FormidableLabs/victory-native#191

[boygirl]

Implementation:

cornerRadius: PropTypes.oneOfType([
    PropTypes.number,
    PropTypes.shape({
      top: PropTypes.number, bottom: PropTypes.number
    })
  ])

When given as a single number it will apply only to the top corners to avoid the breaking change.

[nthegedus]

Sorry but I didn't get how do I implement this. Someone could explain?

I need to use cornerRadius on top and bottom too.

[pixelomo]

@boygirl please give an example of how we implement this, your code just shows what you're changing on the core code