Assisted installer console UI should allow preserving disks not needed by RHOCP

1. Proposed title of this feature request:
--> Preserving other bootable disks from formatting during the RHOCP deployment using the assisted installer

2. What is the nature and description of the request?
--> When the assisted installer gets to the point where it warns "All bootable disks will be formatted during installation" o UI it is possible to expand the storage view to show all the storage that is about to be wiped. For disks showing "Bootable" but showing Role as 'None' there should be a control that allows preserving the content of those disks.

3. Why does the customer need this? (List the business requirements here)
--> With the current situation where there are multiple disks attached to a physical Baremetal node, the customer has either travel physically to the datacenter site to remove media they don't want to be reformatted by the RHOCP installer, or suffer a data loss of other installed test environments which they would otherwise have to re-install. Either approach is an inefficient waste of time.

The wiping of the disks can be avoided by using the assisted-service API and 'aicli' by adding the relevant disks (IDs) to the 'skip_formatting_disks' list however it would be great if we could provide this functionality on the AI Console for inexpert users.

4. List any affected packages or components.
--> Assisted Installer