add support for image pull secrets with backup and restore operations

[tylergmuir]

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• I agree to follow this project's code of conduct.
• I have checked the current issues for duplicates.
• I understand that AWX Operator is open source software provided for free and that I might not receive a timely response.

Feature Summary

When running either a backup or a restore of an AWX deployment, there is a Postgres pod deployed to coordinate the steps. If you are running AWX in an environment where you either want to pull from a private repo or you want to use an authenticated pull from the docker registry you are unable to do that.

The functionality does exist for the initial deployment, so much of the logic can be copied from there.