utils: Introduce managed_bytes<> class
utils: Introduce managed_bytes<> class

It's a bytes container which can be used with LSA.

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