[ENH] PyQtGraph ImageGrid #25
Description
RSoXS has implemented an ImageGrid variant that uses PyQtGraph for way better performance over the matplotlib version. We should re-incorporate that into the built-in nbs-viewer image widgets.
Part of this to-do might be rebalancing what's in the PlotDisplay vs PlotWidget, as we're currently really slanted in favor of the Widget, which has ownership over too much of its own controls, etc.