Add a 'latency_percentile' route/plot
The way this would likely be implemented is to store a small number of latency bins, so that the route would read in the latest snapshot of all bins and plot this. An example of such an implementation is here: https://blog.bramp.net/post/2018/01/16/measuring-percentile-latency/
The main difference between that link and what we want is latency on the y-axis and percentiles on the x-axis. The x-axis would also need to be scaled to emphasize high percentiles like in the example plot above. The transformation used in the plot is 1 - 10**power. If plotly can't do custom axis transformations, then an alternative is to transform the percentiles and then push custom axis ticks/labels.