add bloat checking via continuous ping

[brettowe]

Description

add in a ping function that runs during the loaded part of the test similar to http://www.dslreports.com/speedtest

Why it should be implemented

this gives feedback on quality of the connection and if there is an excessive amount of buffer bloat which can effect things more than just speed. https://en.wikipedia.org/wiki/Bufferbloat https://www.bufferbloat.net/projects/bloat/wiki/

Optional: implementation suggestions

also adding options for multiple streams could be useful on higher bandwidth connections as saturating them might be hard without multiple streams after setting up the background ping its possible adding this subset would be more just a UI item as the backend might get covered otherwise and a passing thought, would having the workers use webrtc browser connections give different stats? so would an option to toggle between connection modes might be interesting also

Optional: screenshots

https://www.dslreports.com/speedtest/70800642 fyi: site needs an account to to create your own ping graphs screenshot shows ping during 'idle' and the range of ping during that time (red bar) then during upload and download tests and the ping range during those. since my connection is well controlled it doesn't show it but if the ping goes above ~135ms the chart changes colors indicating things are not ideal and of course the 'grade' of the connection falls as ping increases