This is a follow up enhancement based on HAC-3850

• As a user I want to be able to view in a dropdown all operator role prefixes associated with the OIDC Config ID I have selected.
• When I select an operator role prefix from the dropdown it should update the provided `rosa create operator-roles` cmd/example.
• I should be able to specify a new operator role prefix to use.

This story is to add the changes to the Operator roles prefix field. 

Acceptance Criteria

• Change the Operator roles prefix field to a Drop Down with the prefix options from the new endpoint being created here - SDA-8330.
• Update the cli command to include the selected value from the new Operator roles prefix dropdown ("<user-defined>"): 

 rosa create operator-roles --hosted-cp --prefix "<user-selected prefix>" --oidc-config-id "<user selected odic-config-id>" 

Open Questions

• Asked a question about the backend enpoint here .