1. Proposed title of this feature request
Support for AvailabilitySets in MachineSets for Azure

2. What is the nature and description of the request?
Customer is deploying OpenShift Container Platform 4 in Microsoft Azure Switzerland. This Azure region does not have multiple zones but is offering instead different AvailabilitySets. Right now MachineSets only support Zones (https://github.com/openshift/cluster-api-provider-azure/blob/release-4.6/pkg/apis/azureprovider/v1beta1/azuremachineproviderconfig_types.go) and customer therefore requested to have support for AvailabilitySets to make sure Machines can be distributed and managed accordingly.

3. Why does the customer need this? (List the business requirements here)
As some Microsoft Azure Region don't provide support for multiple zones, high availability can be achieved to some extends using AvailabilitySets (https://docs.microsoft.com/en-us/azure/virtual-machines/windows/tutorial-availability-sets). Hence to properly use those AvailabilitySets in MachineSets support would need to be added.

4. List any affected packages or components.
cluster-api-provider-azure