Draw current DataPoint on horizontal finger drag

[Pfuster12]

Is your feature request related to a problem? Please describe.
Not an issue.

Describe the solution you'd like
When you trigger the onTouch callback, draw the current DataPoint your finger is closest to and display the Y axis value in a text tag next to it. As the finger drags across horizontally the DataPoint is drawn to match the current value.

A vertical line drawn across from the x axis can be added to help root the DataPoint to the axis.

Version
1.0.0

Current behavior
No support.

Additional context
See Trading 212, Yahoo FInance for similar feature.