PlotlyGraph Widget's Container's height defaults to zero

[umesh-timalsina]

After #1747 was merged, the PlotlyGraphWidget in the case of only one plot defaults to the height of the container. This seems fine in ExecutionIndex, however, in the Log/GraphViewer provides a height of zero.

[umesh-timalsina]

This happens because addNode functions are called before onWidgetContainerResize which sets the height of the container. At this point height's will already be set. The _.debounce function could be levaraged to adjust plot height.