[Feature] Allow strings for XAxis data

Description of feature

The x-axis labels could be a list of strings, right? At least that’s what I have. But I’m getting a

Warning: Failed prop type: Invalid prop data[0] supplied to XAxis.

Because of XAxis.propTypes only allowing numbers and objects for the data array items.

If you agree, I’m willing to make a PR to fix this.

[brendan1809]

i am using formatLabel={index => data[index].yourValue} to call an item in the array

[Gogn]

As JesperLekland mentioned, xAccessor also works well:

<XAxis
                  style={{marginHorizontal: -10, height: xAxisHeight}}
                  data={data}
                  xAccessor={({item}) => item.date}
                  formatLabel={value => moment(value).format("DD-MM-YYYY")}
                  contentInset={{left: 30, right: 30}}
                  svg={{
                    fontSize: 10,
                    fill: 'black',
                    fontWeight: 'bold',
                    rotation: 20,
                    originY: 15,
                    y: 15
                  }}
                />

https://i.imgur.com/ua6v54n.png