db: implement user_types_metadata
db: implement user_types_metadata

This is a simple map of type names to types, with the slight complication
of checking for compatibility when replacing a type.

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