This PR migrates all the add metadata operators to core. This will allow them to be used in other parts of merlin, like systems. These are general operators that manipulate schemas. They are not required to be located in the nvtabular repo. By moving these operators to core, we remove the nvtabular import requirement for these ops.
Should we add these to merlin/dag/ops/__init__.py like the other ops we have in Core? so that they can be imported from merlin.dag.ops instead of requiring an import of this add_metadata module?
This PR migrates all the add metadata operators to core. This will allow them to be used in other parts of merlin, like systems. These are general operators that manipulate schemas. They are not required to be located in the nvtabular repo. By moving these operators to core, we remove the nvtabular import requirement for these ops.