Add confidential VM support on Azure

[HuijingHei]

Feature Request

Feature link: https://issues.redhat.com/browse/OCPSTRAT-366

Desired Feature

Confidential VMs provide protection to data-in-use by encryption the VM memory with keys that Azure doesn't have access to. Those VMs can also be attested by the user.

See Azure Confidential Computing for more details.

Create Confidential VM on Azure using kola, and run tests.

Example Usage

Command like:

cosa kola run --build=38.20230911.20.0 --arch=x86_64 -p=azure --azure-credentials **** --azure-location eastus --azure-disk-uri xxx --security-type ConfidentialVM --size Standard_DC2as_v5 basic

The ConfidentialVM type includes

secureBoot: Enabled
virtualizedTrustedPlatformModule: Enabled
osDisk:
  securityProfile:
    securityEncryptionType: VMGuestStateOnly

Other Information

See :
kubernetes-sigs/cluster-api-provider-azure#3264
openshift/api#1403