[RFE] Rancher Azure Node Driver, add option to set Availability zone on nodes and clusters

[gaktive]

Internal reference: SURE-3319 Reported in 2.5.9

A user would like to be able to deploy nodes templates with an availability zone on Azure. Currently, the node templates handle only the Availability set.

Request description: Add Availability zone to Rancher Azure Node Driver.

Actual behavior: Rancher node driver does not support Azure Availability zones

Expected behavior: Rancher node driver support for Azure Availability zones

Additional notes: Rancher Azure node driver and docker node driver support availability set but not availability zones.

While availability sets are used to protect applications from hardware failures within an Azure data center, Availability zones, protect applications from complete Azure data center failures.

Docker Machine driver support option --azure-availability-set but has no option for availability zones. https://docs.docker.com/machine/drivers/

See also "Availability zones" description at: https://cloudacademy.com/course/getting-started-with-azure-virtual-machines-988/availability-sets-and-availability-zones/

Possible connection with #7164 or in Zube, rancher/dashboard#7164