add properties to key creation request

[dthuering]

Allow per key type setting for HSM-backed storage in Azure

PR description

To support HSM-backed keys in Azure Key Vault, the API payload and service request were extended in a backwards-compatible way to support additional, optional properties. The AKV store supports the AZURE_KEY_VAULT_TYPE property with a value of EC-HSM. When these are set, the key will be backed by HSM in AKV.

Fixed Issue(s)

fixes #579

Changelog

• Added a properties map to the Key Creation API endpoint and service attributes.

• AKV store supports the AZURE_KEY_VAULT_TYPE key and EC-HSM value. That will enable HSM-backed keys.

• [x] I thought about the changelog and included a changelog update if required.

[CLAassistant]

All committers have signed the CLA.