Add computation of bandwidth per line in RateTestHandler
Work towards lhcb-dpa/project#199.
Add an additional webpage to the LHCbPR test page of rate tests, listing the bandwidth of each line in descending order.
Plots of bandwidth distributions are also made.
The bandwidth is computed by rate x event size.
Examples from an Hlt2 and a Sprucing tests can be found here.
cc @nskidmor
Edited by Shunan Zhang