Create management command to populate the initial data galaxy_ng needs.

Motivation

Currently initial data is supposed to be populated using an Ansible Collection: https://galaxy.ansible.com/ansible/galaxy_collection

However, other environments, e.g. container environments and dev environments don't use that, instead they use a fixture-style data population: https://raw.githubusercontent.com/ansible/galaxy_ng/master/dev/automation-hub/initial_data.json

This is problematic because a) we don't have a single source of truth and b) the official way to do it is being ignored in favor of simpler methods.

Solution

Ship a data migration that uses get_or_create to create the data. This would cause new installs to receive it, and existing installs that already have it to be unmodified.