PowerCLI Port of RVC commands vsan.apply_license_to_cluster

This script can be used to:

• Add a license to vCenter if it hasn't already been added
• Assign that license to a specified cluster 

The script includes a function which can be invoked using the following syntax:

Set-VsanClusterLicense -License "XXXXX-XXXXX-XXXXX-XXXXX-XXXXX" -Cluster "ClusterName"

Things to add... For licenses that are per CPU, maybe determine if enough licenses are available.