Handling alias and concept-id metadata in standard commands

[jsheunis]

Currently, the only way to add alias and concept-id metadata is via the script at tools/create_alias_concept_metadata.py. This is not practical, and the existing commands, such as catalog-add etc, should actually be handling creation and maintenance of these redirect files. Possibly also catalog-set for editing a redirect file such that it can be updated to point to the latest version of a given dataset in a catalog.