[FEATURE REQUEST] Add support for Azure availability sets

[mkyc]

Is your feature request related to a problem? Please describe.
We would like to have possibility to create availability-set for Azure using Epiphany in order to have a group with two or more virtual machines in the same Data Center. This ensures that at least one of the virtual machines hosted on Azure will be available if something happens. This configuration offers 99.95% SLA.

Describe the solution you'd like
We would like to have section in cluster yaml file with the availability-set for all components, for example::

kind: infrastructure/availability-set
name: kube-node-availability-set
provider: azure
specification:
  name: kube-node-availability-set
  platform_fault_domain_count: 2
  platform_update_domain_count: 5
  managed: 'true'

Describe alternatives you've considered

Additional context
This task is to manage already existing PR #1411

[rpudlowski93]

Pull Request is already done for the task #1411 and reviewed by @mkyc and @seriva. There are some valuable comments which should be taken into account and maybe added to code. The task must be taken care of by someone and finished based on the review.

[przemyslavic]

The ability to create availability sets was tested. Individual components (virtual machines) can be assigned to the appropriate availability sets. VMs are effectively distributed across fault domains and update domains.