Adding support for galaxy operator

[aknochow]

1. Updating Dockerfile to install required directories in /var/lib/pulp/
2. Adding skopeo dnf dependency for content signing script
3. Adding readyz.py for galaxy-operator ready check

depends-on: ansible/galaxy-operator#17

'No-Issue'

[rooftopcellist]

This changeset looks good.

Idea: I think we might want to think about adding a "configure-signing-services.sh" for the initContainer to use in a future PR to make the operator codebase a bit cleaner.

But a PR for another day.

[rooftopcellist]

@himdel @drodowic @jctanner It looks all of the CI issues pertaining to this PR have been fixed. But the Galaxy CI checks are all failing due to an unrelated problem now when building the image:

    7.066 ERROR: Package 'galaxy-ng' requires a different Python: 3.8.17 not in '>=3.9'
    ------
    Containerfile:8
    --------------------
       6 |     # Install python packages
       7 |
       8 | >>> RUN pip3 install ./galaxy_ng

I see this in other PR's as well for example:

• [AAP-20256] Add organization models #2066

I see this change was made recently... but it is already included in this branch, no need to rebase.

• https://github.com/ansible/galaxy_ng/pull/2048/files#diff-a0aba5a2bd30b2f80a3a18aa24ce43670b1320ca0a8b9c103bb3bc971ae30a85R33

Any suggestions on this issue?

[rooftopcellist]

It appears that the base image used by CI when building has python3.8.17, and python3.9+ is required.

[chadams@awx galaxy_ng]$ docker run -it ghcr.io/pulp/pulp-ci-centos bash

[root@2bfd2acc2a67 /]# python3 --version
Python 3.8.17