Auth aware group and org list action functions should return dictized objects

`organization_list_for_user` and `group_list_authz` create a dict with the Group objects before returning the list, when they should be calling `model_dictize.group_list_dictize` as the rest.

The whole groups list thing is a bit messy, with wrong docstrings, inconsistent docstrings and duplicated code. `organization_list_for_user` , `group_list_authz` and `_group_or_org_list` should all share the same code if possible, that you can be a separate issue.