API: modify column family API to use the histogram
API: modify column family API to use the histogram

With the change in column_family stats, the API needs to get the counter
from the read and write histogram.

It also adds the implementation for the read and write latency histogram.

Signed-off-by: Amnon Heiman <ed5fc74c4692051ad0b19749fd7cea6ec2d74b9e@cloudius-systems.com>

kangkot/scylla,gwicke/scylla,glommer/scylla,kjniemi/scylla,rluta/scylla,aruanruan/scylla,scylladb/scylla,rentongzhang/scylla,capturePointer/scylla,eklitzke/scylla,capturePointer/scylla,kjniemi/scylla,kangkot/scylla,justintung/scylla,scylladb/scylla,victorbriz/scylla,raphaelsc/scylla,acbellini/scylla,scylladb/scylla,shaunstanislaus/scylla,linearregression/scylla,shaunstanislaus/scylla,rluta/scylla,shaunstanislaus/scylla,dwdm/scylla,avikivity/scylla,kjniemi/scylla,glommer/scylla,gwicke/scylla,capturePointer/scylla,bowlofstew/scylla,wildinto/scylla,tempbottle/scylla,wildinto/scylla,acbellini/scylla,avikivity/scylla,linearregression/scylla,eklitzke/scylla,asias/scylla,gwicke/scylla,rentongzhang/scylla,victorbriz/scylla,glommer/scylla,respu/scylla,dwdm/scylla,wildinto/scylla,guiquanz/scylla,linearregression/scylla,raphaelsc/scylla,kangkot/scylla,senseb/scylla,respu/scylla,asias/scylla,duarten/scylla,senseb/scylla,tempbottle/scylla,stamhe/scylla,duarten/scylla,aruanruan/scylla,bowlofstew/scylla,senseb/scylla,guiquanz/scylla,justintung/scylla,guiquanz/scylla,scylladb/scylla,rentongzhang/scylla,justintung/scylla,respu/scylla,duarten/scylla,tempbottle/scylla,rluta/scylla,eklitzke/scylla,phonkee/scylla,raphaelsc/scylla,phonkee/scylla,stamhe/scylla,aruanruan/scylla,avikivity/scylla,acbellini/scylla,asias/scylla,phonkee/scylla,bowlofstew/scylla,dwdm/scylla,stamhe/scylla,victorbriz/scylla