Extend the terraform-hpvs example to illustrate attestation

[Timo-1]

Extend the example to leverage and illustrate attestation:

E.g. add one step for attestation verification, which uses the hpcr Terraform provider feature proposed in ibm-hyper-protect/terraform-provider-hpcr#7

This step verifies the attestation records of the example workload and prints a confirmation if everything is deployed as expected, or issues a warning otherwise.

This way, the examples would show the entire e2e flow from contract creation to attestation validation.

[CarstenLeue]

see ibm-hyper-protect/terraform-provider-hpcr#27 and ibm-hyper-protect/terraform-provider-hpcr#24

[CarstenLeue]

#45