Feature Request: Add onTap

[chitgoks]

Would be nice to have this.

[JHBitencourt]

A callback to add onTap functionality to the default indicator is definitely a good suggestion. The question is if I should ignore it when a custom indicator is provided. Considering that this custom indicator may have its own onTap callback.

[chitgoks]

for now what i did was add gesturedetector on the TimelineTile. and in the indicator property, i replaced it with a circleavatar with iconbutton as child so the indicator is clickable. then set the indicator style to 50,50 width height to have it the same size as your circle default painted canvas.