plotter: EventPlot: Add function to get current context info
plotter: EventPlot: Add function to get current context info

This function uses the co-ordinates provided and binary search
function search_data to get the information about the current
chunk (rectangle visually and an SVG path segment) the mouse
pointer is located over

Signed-off-by: Kapileshwar Singh <d373e2b6407ea84be359ce4a11e8631121819e79@arm.com>

bjackman/trappy,sinkap/trappy,JaviMerino/trappy,ARM-software/trappy,ARM-software/trappy,joelagnel/trappy,sinkap/trappy,ARM-software/trappy,joelagnel/trappy,sinkap/trappy,joelagnel/trappy,JaviMerino/trappy,joelagnel/trappy,ARM-software/trappy,JaviMerino/trappy,bjackman/trappy,bjackman/trappy,bjackman/trappy,sinkap/trappy