armpolicy: Azure Policy Exemptions

### Feature Request Since the `ExemptionsClient` was deleted from `armpolicy` in version `1.0.0`, how are we meant to create exemptions if we want to migrate to `armpolicy` 1.0.0? I could not find any reference as to how we can create Policy Exemptions since that release and would love for this feature to come back as we are using it extensively in our company.