Description of problem:

The current "Installing Red Hat Developer Hub in an air-gapped environment" docs for installing and operating RHDH in a disconnected environment are specific to OpenShift.

https://docs.redhat.com/en/documentation/red_hat_developer_hub/1.4/html/installing_red_hat_developer_hub_in_an_air-gapped_environment/index 

• The Operator docs have prerequisites on OCP and use resources that are OCP-specific: https://docs.redhat.com/en/documentation/red_hat_developer_hub/1.4/html/installing_red_hat_developer_hub_in_an_air-gapped_environment/proc-install-rhdh-airgapped-environment-ocp-operator_title-install-rhdh-air-grapped#proc-install-rhdh-airgapped-environment-ocp-operator_title-install-rhdh-air-grapped
• The Helm Chart docs are relying on the internal OCP registry and rely on ImageStreams, which are OCP-specific: https://docs.redhat.com/en/documentation/red_hat_developer_hub/1.4/html/installing_red_hat_developer_hub_in_an_air-gapped_environment/proc-install-rhdh-airgapped-environment-ocp-helm_title-install-rhdh-air-grapped#proc-install-rhdh-airgapped-environment-ocp-helm_title-install-rhdh-air-grapped 

Steps to Reproduce

1. Try to follow the airgap procedure against a non-OCP disconnected cluster: https://docs.redhat.com/en/documentation/red_hat_developer_hub/1.4/html/installing_red_hat_developer_hub_in_an_air-gapped_environment/index 

Actual results:

The current procedure won't work on non-OCP clusters.

Expected results:

Since we are claiming support for other non-OCP platforms like EKS, AKS, GKE, we should provide instructions for airgapping these platforms as well.

Reproducibility (Always/Intermittent/Only Once):

Always

NOTES:

• The script mentioned in the Operator airgapping docs is being updated in RHIDP-5230 to support different use cases like the ability to work on all supported platforms and support partially and fully disconnected environments
  • The Operator docs could be updated accordingly: https://docs.redhat.com/en/documentation/red_hat_developer_hub/1.4/html/installing_red_hat_developer_hub_in_an_air-gapped_environment/proc-install-rhdh-airgapped-environment-ocp-operator_title-install-rhdh-air-grapped#proc-install-rhdh-airgapped-environment-ocp-operator_title-install-rhdh-air-grapped 
• RHIDP-5350 is updating the Helm chart procedure to use oc-mirror, as the recommended way for airgapping on OCP. But this is OCP-specific at this time.
  • => We should provide instructions (or a script) that would work on non-OCP clusters and document accordingly