Test latest CKF in an airgapped environment

[kimwnasptd]

We need to test the current CKF in an airgapped environment to gather list of issues that block it's deployment.

In the past we've worked on 3 areas for this:

1. Automate testing CKF in an airgapped environment #678
2. Ensure our Charms don't do apt install in their code feat: Remove apt-install from Dex Charm dex-auth-operator#148
3. Extend our Charms to be able to configure all the images the charmed container might deploy

The last piece is to know do a pass and test the latest/edge bundle in an airgapped environment and gather list of issues we will find.

[kimwnasptd]

Until #679 is resolved though we'll need to manually find the list of images, to use when deploying the bundle

[kimwnasptd]

We'll also need to pay extra care to

• Istio feat: configurable images istio-operators#316
• Knative Test Knative in airgapped CKF knative-operators#140

As exposed in #680 (comment), since they use an operator to handle the installation.

For those two, if we are time pressured, we can still document a workaround on getting them to work on airgapped by updating the manifests after the installation.

[i-chvets]

Istio configurable images implementation is tracked here