WIP WIP WIP. Started working on U4-5648 which led to quite a lot of other things, once IDataType was removed (U4-5858), this lead to U4-5546, U4-5416, U4-5484, U4-5805. So much of this stuff is etched deep into the codebase, so nice to get rid of it. Had to remove the codefirst tests too for now since they relied on old apis and we don't really support it/use it. Commented out all of the code relating to the document type editor UI bits since they need to be rewritten and removed.