Add pull-secret flag to HyperShift install CLI

User Story:

As a HyperShift CLI user, I want to be able to:

• include my pull secret when installing the HyperShift operator with an externalDNS setup

so that I can achieve

• the ability to pull the Red Hat version of the externalDNS image.

Acceptance Criteria:

Description of criteria:

• The ability to include the pull secret on a HyperShift operator installation is available in the HyperShift CLI

Out of Scope:

• Any additional changes needed to install HCPs on AKS

Engineering Details:

• N/A

This requires/does not require a design proposal.
This requires/does not require a feature gate.