Given the APIs are not yet available on stage env, this task covers the initial work on the UI to support GCP Workload Identity Federation using mocked APIs only.

More tickets will follow to verify and update the UI after wif_configs endpoints will be ready.

See parent OCMUI-1616 for more info. 

Acceptance criteria:

• New WIF authentication method is available when creating OSD GCP CCS clusters behind and it's enabled on stage behind a feature flag
• WIF config client side validation works as expected using mocked APIs
• No regressions when creating OSD GCP CCS clusters using service account (old authentication method).